Scientific diving is the use of underwater diving techniques by scientists to perform work underwater in the direct pursuit of scientific knowledge. The legal definition of scientific diving varies by jurisdiction. Scientific divers are normally qualified scientists first and divers second, who use diving equipment and techniques as their way to get to the location of their fieldwork. The direct observation and manipulation of marine habitats afforded to scuba-equipped scientists have transformed the marine sciences generally, and marine biology and marine chemistry in particular. Underwater archeology and geology are other examples of sciences pursued underwater. Some scientific diving is carried out by universities in support of undergraduate or postgraduate research programs, and government bodies such as the United States Environmental Protection Agency and the UK Environment Agency carry out scientific diving to recover samples of water, marine organisms and sea, lake or riverbed material to examine for signs of pollution.
Equipment used varies widely in this field, and is generally selected based on cost, effectiveness, availability and risk factors. Open-circuit scuba is most often used as it is widely available and cost-effective, and is the entry level training mode in most places.
Scientific diving in the course of employment may be regulated by occupational safety legislation, or may be exempted as self-regulated by a recognised body. The safety record has generally been good. Collection of scientific data by volunteers outside of employment is generally considered to legally be recreational diving.
Training standards vary throughout the world, and are generally higher than for entry level recreational diving, and in some cases identical to commercial diver training. There are a few international agreements that facilitate scientists from different places working together on projects of common interest, by recognising mutually acceptable minimum levels of competence.
Scientific diving is any diving undertaken in the support of science, so activities are widely varied and may include visual counts and measurements of organisms in situ, collection of samples, surveys, photography, videography, video mosaicing, benthic coring, coral coring, placement, maintenance and retrieval of scientific equipment.
Underwater diving interventions, particularly on scuba, provide the capacity for scientists to make direct observations on site and in real time, which allow for ground-truthing of larger scale observations and occasional serendipitous observations outside the planned experiment. Human dexterity remains less expensive and more adaptable to unexpected complexities in experimental setup than remotely operated and robotic alternatives in the shallower depth ranges. Scuba has also provided insights which would be unlikely to occur without direct observation, where hypotheses produced by deductive reasoning have not predicted interactive and behavioural characteristics of marine organisms, and these would not be likely to be detected from remote sensing or video or other methods which do not provide the full context and detail available to the diver. Scuba allows the scientist to set up the experiment and be present to observe unforeseen alternatives to the hypothesis.
The field of global change biology includes investigation of evidence relating to global warming and ocean acidification. Many of the measurable changes in global climate occur in the sea. Coral bleaching is an example of an indicator of change, and scuba diving has provided a large amount of low-impact observational data contributing significantly to the large body of knowledge on the subject over several decades.
The field of ocean acidification and the impact of anthropogenic carbon dioxide emission has seen similar growth and most of the cited articles in this field have relied to a significant extent on data collected during scuba diving operations.
The field of paleoclimate reconstruction has a major influence on the understanding of evolution and the ecological and biogeographic past, as climate is the most powerful driver of evolution. Coring corals on a reef in the least harmful and focused manner is currently most practicable using scuba technology. This mining of the past makes it possible to attempt to predict future climate.
Advances in training and accessibility to trimix diving and closed circuit rebreather systems has enabled scientific divers to reach highly diverse deeper mesophotic reefs which may be the corals last refuge from the warming of surface waters.
The current knowledge of the functioning of the ecologically and economically important hard-bottom communities in the shallow water coastal zones is both limited and particularly difficult to study due to poor accessibility for surface operated instrumentation as a result of topographic and structural complexity which inhibit remote sampling of organisms in the benthic boundary layer. In situ assessments by scientific divers remain the most flexible tool for exploring this habitat and allow precise and optimised location of instruments.
The capacity to dive under polar ice provides an opportunity to advance science in a restricted environment at relatively low cost. A small number of holes in the ice can provide access over a large area and high levels of experimental replication. Divers are a flexible and reliable method for deploying, maintaining and retrieving equipment from under‐ice environments, and are relatively cost efficient for researching remote locations that, would otherwise require the use of more expensive research vessels.
The global threat to marine ecosystems due to over‐exploitation, habitat loss, pollution and climate change is exacerbated by introduction of alien species, which is considered to be one of the leading causes of extinctions and biodiversity loss. Scientific divers are the most competent to detect the presence of potentially invasive species and in some cases can provide a quick response. Monitoring the effectiveness of response also requires diver intervention.
Scientific diving may use any mode of diving that is best suited to the project. Scientific diving operations may use and have used freediving, scuba open circuit, scuba closed circuit, surface oriented surface-supplied systems, saturation diving from surface or underwater habitats, atmospheric suit diving or remotely operated underwater vehicles. Breathing gases used include air, oxygen, nitrox, trimix, heliox and experimental mixtures.
Several citizen science projects use observational input from recreational divers to provide reliable data on presence and distribution of marine organisms. The ready availability of digital underwater cameras makes collection of such observations easy and the permanence of the record allows peer and expert review. Such projects include the Australian-based Reef Life Survey, and the more international iNaturalist project, based in California, which is only partly focused on marine species.
Scientific diving operations which are part of the work of an organisation are generally under the control of a diving supervisor or equivalent, and follow procedures similar to other professional diving operations.
A scientific diving operation which follows the usual procedures of a commercial scuba operation will include one or more working divers, a stand-by diver and a supervisor, who will manage the operation from the surface control point. If the divers are tethered, there will generally be a line tender for each tethered diver in the water The stand-by diver may remain out of the water at the surface or may accompany the working diver or divers in the water. Surface supplied and saturation operations will also generally follow standard procedures used by commercial divers.
The American system has a Diving Control Board taking overall responsibility for all scientific diving work done by an organisation. The Diving Officer is responsible to the board for operational, diving and safety matters. For each dive, one scientist, designated as the Lead Diver, must be present at the site during that entire operation, and is responsible for management of the dive, including dive planning, briefing, emergency planning, equipment and procedures. The divers operate in a strict buddy diving system.
The standard procedures for scuba and surface supplied diving are essentially the same as for any other similar diving operation using similar equipment in a similar environment, by both recreational, technical and other professional divers. There are a few special cases where scientific diving operations are carried out in places where other divers would generally not go, such as blue-water diving. Scientific dives tend to be more task oriented than recreational dives, as the scientist is primarily there to gather data, and the diving is of secondary importance, as the way to get to the worksite.
The requirements for qualification as a scientific diver vary with jurisdiction. The European Scientific Diver (ESD) standard is reasonably representative:
Basic skills and underlying knowledge must include:
Emergency skills include competence in:
The requirements for qualification as a scientific diver vary with jurisdiction. The European Scientific Diver (ESD) standard is reasonably representative:
Competence in work methods common to scientific projects:
Underwater navigation by divers is broadly split into three categories. Natural navigation techniques, and orienteering, which is navigation focused upon the use of an underwater magnetic compass. and following a guideline.
Natural navigation, sometimes known as pilotage, involves orienting by naturally observable phenomena, such as sunlight, water movement, bottom composition (for example, sand ripples run parallel to the direction of the wave front, which tends to run parallel to the shore), bottom contour and noise. Although natural navigation is taught on courses, developing the skills is generally more a matter of experience.
Orienteering, or compass navigation, is a matter of training, practice and familiarity with the use of underwater compasses, combined with various techniques for reckoning distance underwater, including kick cycles (one complete upward and downward sweep of a kick), time, air consumption and occasionally by actual measurement. Kick cycles depend on the diver's finning technique and equipment, but are generally more reliable than time, which is critically dependent on speed, or air consumption, which is critically dependent on depth, work rate, diver fitness, and equipment drag. Techniques for direct measurement also vary, from the use of calibrated distance lines or surveyor's tape measures, to a mechanism like an impeller log, to pacing off the distance along the bottom with the arms.
Skilled underwater navigators use techniques from both of these categories in a seamless combination, using the compass to navigate between landmarks over longer distances and in poor visibility, while making use of the generic oceanographic indicators to help stay on course and as a check that there is no mistake with the bearing, and then recognising landmarks and using them with the remembered topography of a familiar site to confirm position.
Guidelines, also known as cave lines, distance lines, penetration lines and jackstays are permanent or temporary lines laid by divers to mark a route, particularly in caves, wrecks and other areas where the way out from an overhead environment may not be obvious. Guidelines are also useful in the event of silt out.
Distance lines are wound on to a spool or a reel. The length of the distance line used is dependent on the plan for the dive. Reels for distance lines may have a locking mechanism, ratchet or adjustable drag to control deployment of the line and a winding handle to help keep slack line under control and rewind line. The material used for any given distance line will vary based on intended use. The use of guideline for navigation requires careful attention to laying and securing the line, line following, marking, referencing, positioning, teamwork, and communication.
A transect line is a special case of a guideline commonly used in scientific diving. It is a line laid to guide the diver on a survey along the line. In cases where position along the line must be accurately specified, a surveyor's tape or chain may be used as the transect line.
Searches are often required to find the subject of study, or to recover previously placed instrumentation. There are a number of techniques in general use. Some of these are suitable for scuba, and some for surface supplied diving. The choice of search technique will depend on logistical factors, terrain, protocol and diver skills.
As a general principle, a search method attempts to provide 100% coverage of the search area. this is greatly influenced by the width of the sweep. In conditions of zero visibility this is as far as the diver can feel with his hands while proceeding along the pattern. When visibility is better, it depends on the distance at which the target can be seen from the pattern. In all cases then, the pattern should be accurate and completely cover the search area without excessive redundancy or missed areas. Overlap is needed to compensate for inaccuracy, and may be necessary to avoid gaps in some patterns. Common search patterns include:
Most scientific fieldwork involves some form of data collection. In some cases it is on-site measurement of physical data, and sometimes it involves taking samples, usually recording the circumstances in some detail. Video, still photography and manual listing of measurements and labeling of specimens are common practice. Biological and geological specimens are usually bagged and labelled for positive identification, and the availability of underwater cameras allows in-situ and bagged photographs to be taken for reference Biological specimens may also be tagged an released, or have small biopsies taken for DNA analysis. When non-extractive measurements are made, video and still photography provide backup for listed data. Recording on prepared sheets is preferred where practicable as writing underwater is relatively inefficient, and often not very legible. Waterproof paper on a clipboard or a waterproof slate are commonly used for written records. Ordinary graphite pencils work fairly well underwater, though the wood tends to split after a while.
Types of survey:
Mapping of an underwater site may be necessary for analysis of the data. Several methods are available. A map is the two or three dimensional representation of geographic survey data following a standardised format, often using symbolic representations of data, and often to a specified scale.
Generally relatively low risk and good safety record overall, the vast majority of dives are relatively shallow and in reasonably good conditions. Most scientific dives can be deferred when conditions are sub-optimal, and seldom require the use of dangerous equipment. This has allowed a good safety record in spite of relatively relaxed equipment and training requirements for occupational diving.
The earliest scientific diving safety programme in the US was established at the Scripps Institution of Oceanography in 1954, about 5 years before the development of the national recreational scuba training agencies. Most American scientific diving programmes are based on elements of the original Scripps diving programme.
A survey of some half a million scientific dives reported 7 fatalities and 21 cases of decompression illmess. These rates are lower than those previously reported for military personnel, recreational divers in the UK, recreational divers in the Caribbean, recreational divers in western Canada and wreck divers in cold water.
Nitrox has been used for open circuit scientific diving since the early 1970s with no evidence of increased DCS risk in comparison with similar air dives.
A maximum oxygen partial pressure of 1.6 bar has been found generally acceptable for open circuit nitrox diving by the scientific community, and it has not been found necessary to screen for carbon dioxide retention.
Investigation of the order of dive profiles has shown no statistical increase of decompression sickness risk in reverse profile diving. No validity was found for the rule of diving progressively shallower in successive no-decompression dives imposed by recreational diver training organisations.
As of 1992 the prevalence of decompression illness in the United States was estimated at one case per 100,000 dives for the scientific diving community. This may be compared with approximately one case per 1000 dives for commercial diving and one case per 5000 dives for recreational diving. The reported decompression sickness rate of 1:100,000 over 50 years appears to be acceptable to the scientific diving community. Diving profiles resemble recreational diving more than other sectors, but the incident rate in scientific diving is an order of magnitude lower than for recreational diving. This has been attributed to more thorough entry-level and continued training, better supervision and operational procedures and medical and fitness screening.
In the United States scientific diving is done by research institutions, universities, museums, aquaria, and consulting companies for purposes of research, education and environmental monitoring. As of 2005 there were an estimated 4000 scientific divers, of which a small number are career scientific divers, with an average age of around 40 years, and a larger number of students in the 18 to 34 year age group. There is no specific upper age limit providing the diver remains medically fit to dive. The lower limit is determined by the age of students qualifying for training. About a quarter are female.
In the US, scientific diving is exempted from the requirements of the Federal Occupational Safety and Heath regulations, provided that it complies with the requirements specified for the exemption.
Scientific diving governance organizations include:
When a scientific diving operation is part of the duties of the diver as an employee, the operation may be considered a professional diving operation subject to regulation as such. In these cases the training and registration may follow the same requirements as for other professional divers, or may include training standards specifically intended for scientific diving. In other cases, where the divers are in full control of their own diving operation, including planning and safety, diving as volunteers, the occupational health and safety regulations may not apply.
Where scientific diving is exempt from commercial diving regulation, training requirements may differ considerably, and in some cases basic scientific diver training and certification may not differ much from entry level recreational diver training.
Technological advances have made it possible for scientific divers to accomplish more on a dive, but they have also increased the complexity and the task loading of both the diving equipment and the work done, and consequently require higher levels of trainng and preparation to safely and effectively use this technology. It is preferable for effective learning and safety that such specialisation training is done systematically and under controlled conditions, rather than on site and on the job. Environmental conditions for training should include exercises in conditions as close as reasonably practicable to field conditions.
Although the first scientific diving expedition in Australia was carried out by Sir Maurice Yonge to the Great Barrier Reef in 1928, most scientific diving did not start until 1952 when the Commonwealth Scientific and Industrial Research Organisation began work to understand the pearl beds of northern Australia in 1957. Commercial divers worked under Australian Standard CZ18 "Work in Compressed Air" in 1972. This standard applied to caisson workers and divers so the underwater work was drafted into AS 2299 "Underwater Air Breathing Operations" in 1979. In 1987, a re-write of AS 2299 included scientific diving in the regulations even though the divers had been self-regulating under the Australian Marine Sciences Association (AMSA). At that time, the AMSA and the Australian Institute for Maritime Archaeology (AIMA) began a collaboration to draft a new standard for scientific diving.
In the 1960s there were no regulations for scientific diving in Germany, but two fatal accidents in 1969 led to the implementation of guidelines for scientific diving based on the commercial diving guidelines. These define the equipment, training, protocols and legal background for scientific diving for German universities, research institutes and government organisations. Divers trained to these requirements are mostly science students or technicians, and are subsequently registered as scientific divers.
Scientific diving is done by a tethered diver in the water, monitored by a dive tender at the surface, controlled by a dive operation leader (supervisor) and with a standby diver on site. Diving equipment includes full-face mask and dry suit, but a buoyancy control device is not obligatory. Most dives do not require decompression stops.
In South Africa, scientific diving is considered a form of commercial diving and is within the scope of the Diving Regulations 2009 and the Code of Practice for Scientific Diving published by the Chief Inspector of the department of Labour, Under DR 2009 the Codes of Practice are guidance and not compulsory practice. They are provided as recommended good practice, and in theory need not be followed providing an acceptable level of safety is achieved in terms of the Occupational Health and Safety Act #85 of 1993. However, in this case the onus is on the diving contractor to ensure acceptable safety during the diving operation based on risk assessment. The level of safety required is specified in the OHS act as "reasonably practicable" taking into account a number of factors, including cost effectiveness, availability of technology for mitigation and available knowledge of hazards. Use of the relatively flexible scientific code rather than the default Code of Practice for Inshore Diving is restricted to clients which are registered as organisations engaged in either scientific research or higher education.
The qualification required to dive at work in South Africa is linked to the mode of diving, the equipment to be used, and the diving environment. There are six classes of occupational diver registration, all of which may be employed in scientific diving operations within the scope of the specified competence and when supported by the required infrastructure.
In each of these classes, the fundamental diving or supervisory competences include those of the class with the next higher number, though specialist skills may differ from person to person and may have no obvious connection to the registered class. All scientific dives must be under the supervision of a registered diving supervisor of a class appropriate to the specific diving operation.
Most scientific diving in South Africa is done on open circuit scuba by Class 4 and 5 divers as no-stop dives on air or nitrox. The Code of Practice for Scientific Diving allows for the use of alternative modes and technologies provided appropriate competence is achieved by training and assessment, and the risk of the project is assessed as acceptable by both the organisation and the members of the diving team. Minimum personnel requirements are as stated in the Diving Regulations, and may only be varied under authorisation of an exemption from the Chief Inspector of the Department of Employment and Labour.
As diving is an activity that is considered to put the diver at a higher than normal risk to health, in the UK all diving at work, including scientific diving, is regulated through the Diving at Work Regulations, 1997 and the associated approved codes of practice, which are implemented by the Health and Safety Executive. The code of practice for scientific diving also covers archaeological diving and diving in public aquariums. The professional body representing the scientific and archaeological diving sector is the Scientific Diving Supervisory Committee (SDSC), and it is responsible to the Natural Environment Research Council
The determining factors indicating that a person is diving at work, and therefore are subject to the regulations, are:
HSE regulations are only enforceable within UK waters, but operations from UK registered merchant vessels may also require adherence to the regulations and codes of practice.
Undergraduate students and volunteers are generally not regarded as being at work, but if diving as part of an organised event or programme, the diving contractor will still have a duty of care. Postgraduate students are more likely to be considered at work when the diving is a significant part of their research.
In the United States scientific diving is permitted by the Occupational Safety and Health Administration to operate under an alternative consensual standard of practice that is maintained by the American Academy of Underwater Sciences.
29 CFR Part 1910 - Subpart T "Commercial Diving Operations," establishes mandatory occupational safety and health requirements for commercial diving operations which apply wherever OSHA has statutory jurisdiction. This covers the inland and coastal territorial watrs of the United States and possessions. 
The United Brotherhood of Carpenters and Joiners of America petitioned the Federal Government in 1975 to issue an emergency temporary standard covering all professional diving operations, which was issued on June 15, 1976, to be effective from July 15, 1976. This was challenged in the US Court of Appeals and was withdrawn in November 1976. A permanent standard for commercial diving was subsequently formulated which became effective from October 20, 1977. The American Academy for Underwater Science applied for an exemption for scientific diving, citing 20 years of self-regulation and a lower accident rate than the commercial diving industry. An exemption was issued effective from November 28, 1982, after negotiation.
To be able to avail itself of the Scientific Diving Exemption the institution under whose auspices the work is carried out must meet four tests:
The AAUS promulgates and regularly reviews the consensus based Standards for Scientific Diving Certification and Operation of Scientific Diving Programs, which is a guideline for scientific diving programs in the US, and also used in some other countries. this document is currently the "Standard" of the scientific diving community and must be followed by all organizational members, these standards allow for reciprocity between institutions, and are widely used throughout the United States and some foreign countries.
The AAUS uses three levels of scientific diver authorisation:
There are also depth limitations which may be incrementally increased based on satisfactory experience, for 9 msw, 18 msw, 30 msw, 40 msw 45 msw and 58 msw. A range of specialty qualifications may follow additional training and assessment. These are: decompression diving, surface-supplied diving, mixed-gas diving, nitrox diving, rebreather diving, lock-out and saturation diving, blue-water diving, drysuit diving, overhead environment diving, altitude diving, and use of dive computers for decompression monitoring.
Various methods may be used to allow for international recognition of scientific divers, allowing them to work together on projects. In some cases the professional diver qualifications may be mutually recognised between countries, and in other cases the exemption allows the controlling bodies to make the necessary arrangements.
The European Scientific Diving Panel (ESDP) is the European platform for the advancement of underwater scientific excellence and to promote and provide a practical support framework for scientific diving at a European scale. The ESDP was initiated in 2008 as a European Marine Board Panel (until April 2017) and currently is receiving organizational support from the European network of Marine Stations (MARS).
The following countries are members of the ESDP as of 2019:
The ESDP is intended to maintain and develop a system for recognition of scientific diving competencies issued by member states, which may be issued under various training routes and levels of national legislation, to facilitate participation and mobility by diving scientists in European research programmes, and to improve diving safety, quality of science, and underwater techniques and technologies.
Two levels of scientific diver registration are recognised. These represent the minimum level of training and competence required to allow scientists to participate freely throughout the countries of the European Union in underwater research projects diving using scuba. Certification or registration by an authorized national agency is a prerequisite, and depth and breathing gas limitations may apply.
This competence may be gained either through a formal training program, by in the field training and experience under appropriate supervision, or by a combination of these methods. These standards specify the minimum basic training and competence for scientific divers, and do not consider any speciality skill requirements by employers. Further training for job-specific competence is additional to the basic competence implied by the registration.
All member countries of the European Union are expected in terms of directive EEC 92/51 to recognise one or both of these training levels. An applicant who satisfies the requirements will be issued with either an ESD or an AESD certificate that is valid for five years, and must be renewed every five years by application to the issuing authority. The certificate holders must comply with all national and local rules regarding medical fitness, workplace safety, insurance, and limitations on scientific diving activities when engaged in scientific diving in a host member country. The certificate only indicates previously assessed competence to the training level, and not the current level of competence.
Divers inspecting a stereo BRUVS frame at Rheeder's Reef in the Tsitsikamma National Park MPA
A biologist records algal diversity within a photoquadrat during an underwater survey at Midway Atoll. Hawaii, Northwestern Hawaiian Islands.
Collecting samples of the Eurasian Watermilfoil (Myriophyllum spicatum) plant which threatens fish in Sandy Lake
Navigation by reference to terrain features, both natural and artificial, usually with the aid of an appropriate chart.