Following are a few tips on how one may best behave while diving in the company of sharks. These tips are based largely on my shark diving experience to date (thousands of dives with about 40 species of sharks [I'd have to check my diving logbooks to come up with a firm number] in many locations around the globe and under a wide variety of diving conditions). I hope you will find them interesting and useful.
* Be prepared. Learn what kinds of sharks you are likely to encounter in the area in which you plan to dive and know something of what to expect of each species' behaviour. Bear in mind that maintaining diver safety becomes significantly more difficult with decreasing visibility (such as at night or in turbid water) and with increasing depth, current, task loading (such as carrying an underwater camera, speargun, or other equipment) and number of sharks. Never allow yourself to forget that the ocean itself is far more dangerous than any shark. Know your own limitations, and dive within them. Discuss dive logistics and contigency plans (hand signals, site analysis, entry and exit considerations, separation procedures, etc.) with your dive buddy *before* you enter the water.
* While diving, try to behave like a well-mannered 'guest' - remember that you are a visitor in the shark's living room. Let any shark you encounter approach and investiagte you on its own terms. Do not chase, corner, grab, knife, spear, or touch the shark in any way; it is a wild animal that *will* defend itself if it perceives itself to be threatened (though in all likelihood, if you do behave in a way that seems threateninmg to it, the shark will simply swim away, rather than snap at or bite you - but it's best to not take that chance or otherwise force the issue).
* Try to avoid staring directly at the shark. (In my experience, sharks are very aware of a diver's eyes and seem to dislike being stared at as much as you or I do.) Instead, watch it from 'the corner of your eyes'. For your own safety, however, it is important that you do not loose sight of the shark while it is in your immediate vicinity. Remain vigilant for several minutes after the shark has apparently left, to be sure that it has, in fact, gone.
* During your ecounter with a shark, remain motionless - preferably on or near the bottom (try to become an unthreatening 'part' of the natural bottom topography); large or rapid movement on the part of a diver often frightens a shark into fleeing and may startle it into defensive attack.
* Reduce your vertical profile in the water; crouch down on or near the bottom or orient yourself horizontally in the water column (sharks often seem more unnerved by height than length - perhaps because the vast majority of creatures it encounters are longest horizontally, in the direction of travel).
* Avoid clustering with other divers (sharks often seem to perceive tightly packed groups of divers as a single, large, and altogether frightening super-organism). Remain close enough to your buddy to maintain safety, but relatively far away from other such buddy pairs. Leave solo diving with sharks to the professionals.
* To prolong your encounter, take advantage of the shark's natural curiosity. Try humming quietly into your regulator (almost any tune with a simple but not-too-regular rhythm works pretty well - I've had good results with "Waltzing Matilda", but the theme from "Gilligan's Island" may be more to your tastes. Let me know how it works out). Or try clinking two rocks together or clanging the butt of your dive knife against your scuba tank - these simple techniques are sometimes quite successful in luring a curious shark closer to investigate. If you have a brightly-coloured camera housing or reef glooves, they may also help pique a shark's curiosity - but do not attempt to gesture while wearing such glooves: they may look edible to a shark.
* Do not use bait or otherwise attempt to feed a shark while underwater. Feeding contexts radically change the character of a shark's investigative behaviour, and may lure other sharks, adding a competitive 'wild card' factor to the mix. Under such conditions, a shark encounter can change from wonderful and serene to downright dangerous in a fraction of a heartbeat. Leave shark feeding and working with baited sharks to the professionals.
* If you must surface while a shark is in your immediate vicinity - due, for example, to low air supply: move slowly and deliberately, never loosing sight of the shark. Swim directly to your pre-planned exit site. Avoid a long surface swim, which is tiring and may leave you vulnerable to attack from below; when you arrive at your exit point (boat, dock, beach, whatever), do not dawdle - exit the water smoothly but efficiently. (Incidentally, if you spot a shark from the surface and choose to dive with it, enter the water quietly, using a controlled seated entry rather than a giant stride entry - not only are you less likely to frighten away any nearby shark, but I have seen sharks react with great excitement to the commotion caused by such a spectacular, noisy entry; in an excited state, a shark can become dangerous in an instant.)
* Observe the behaviour of the shark very carefully. If it appears excited or aggitated (quick, jerky movements; pectoral fins held stiffly downward; abrupt change in swimming style; overall increase in muscular tension) or otherwise begins to swim in an erratic manner, leave the water immediately (following the guidelines outlined above); in all likelihood, by increasing the distance between you and the shark, it will relax somewhat and either make good its escape or return to its former, more languid cruising style. It may be relatively safe to remain in the water after that, but prudence dictates a slow but efficient exit from the water (again, following the guidelines above).
* Be aware of the behaviour of fishes and other creatures in the immediate area: if they suddenly dive for cover, appear to behave erratically or in an aggitated manner, leave the water immediately (following the basic guidelines outlined above). Trust your diver instincts - if something just doesn't 'feel' right about the situation, leave the water immediately.
Above all, enjoy the experience. You will almost certainly remember the encounter long after the shark has forgotten you.
Richard Martin is a former shark fisheries biologist turned marine educator. He frequently gives humourous talks on marine biological subjects at aquaria, museums, and dive trade shows, and has written and illustrated over 90 articles and columns for various national magazines as well as two books, Shark Smart: the Divers' Guide to Understanding Shark Behaviour and Do Whales Fart? And Other Questions. Martin's current research focuses on the behavioural ecology of tropical reef sharks and the biology of deep-sea sharks. He is the the founding director of ReefQuest Expeditions (an eco-tourism company which conducts credit and non-credit courses in marine natural history at select locations throughout the tropical Pacific), as well as a member of the American Elasmobranch Society and the National Marine Educators Society. Martin lives in Vancouver, Canada, and is busily working on a new book. Copyright 1998 Richard Martin. All Rights Reserved.