A large temperate-water shark, grey above and white below, met by divers almost only on organised trips to known aggregation sites.
Heavy-bodied, grey to grey-brown above with a sharp line to a white belly, a conical snout and a large first dorsal fin. Adults are commonly three to five metres.
It is a cool and temperate water animal, found off South Africa, southern Australia, California, Mexico and the north-east Atlantic. Most divers who see one have travelled to do so and are in a cage. Encounters on ordinary recreational dives are very rare, and the animal is not a consideration when planning normal diving anywhere.
Where it is dived deliberately, the risk is managed by the operator and by the structure the diver is in. The sensible advice is the same as for any large shark: stay vertical in the water, keep the animal in sight, do not swim away at the surface, and follow the briefing you were given rather than the one you read somewhere else.
This entry carries no occurrence record. The animal is listed because it is a hazard a diver should be able to look up, and its range is given above, but none of the destinations this site holds data for is inside that range. A record will be added when there is one to add rather than an estimate to invent.