A largely unexplored area, the Burma Banks are a series of large underwater flat-topped sea-mounts that lie approximately 180 kilometres (100 nautical miles) northwest of the Similan Islands. The Banks' surrounding waters are over 350 metres deep and large areas rise to within the depth limits of recreational scuba diving.
The name derives from the fact that this 1,500 square kilometre area lies within the exclusive economic zone of Burma. The Banks offer some exciting, stimulating diving, but since this is true open-ocean diving, they certainly are not for everyone.
These mountains rise very gradually from the depths and are covered with hard coral growth and large patches of sand. Although the huge plate corals (some of these 'plates' could seat all the knights of the round table easily) are in many areas fantastic, that is not the reason for travelling so far out to sea. After all, the Similans and the islands north of them boast of some of the loveliest coral in the world. No, the reason for diving all the way out here is for what the Similans don't have; BIG ANIMALS-and that means big sharks as well.
Close shark encounters are virtually guarantied here. The most common type of shark is the nurse shark that grows to over 3 metres in length. Where else can you go to see tens of large nurse sharks freely swimming nose-to-tail over the top of the reef on every dive, which have so little fear of divers that they sometimes accidentally swim harmlessly (for both parties) into us? They are truly the clowns of the banks as it is difficult not to laugh at their frenzied movements. Not enough? How about large silver tip sharks that when attracted by bait swim within range of your Nikon's 15 mm lens?
If the nurse sharks are the clowns, then the silver tips are the stars. Reaching an impressive length of two to three metres, these sharks -- often compared to the Galapagos shark and easily identified by the white trailing edge on their pelvic, dorsal, and caudal fins -- are full-bodied, serious predators. Although cautious by nature, and certainly not aggressive towards divers, these sharks are spotted on virtually every dive. And these days, all three of the diving companies that visit the banks feature a controlled shark attraction by placing fish in the water down current from all divers, baiting the sharks in for an up-close, personal look.
These attractions offer the opportunity to photograph these silver tips and nurse sharks, with the occasional tiger or hammer head making an appearance. In addition, you'll see larger reef fish than in other areas of Thailand, such as huge sweet lips and the occasional grouper. The most common diving technique at the banks are large drift dives over the mountain flats. Currents can be quite tricky here-sometimes changing in direction 90º to 180º very quickly - and very fast. It is common to drift over one kilometre on certain dives - assuming the current is taking you in the direction you originally planned! All dive operators that dive at the banks are strict with safety rules.
Although these vary slightly from operator to operator, it is roughly agreed that all divers must dive with a 'safety sausage', a whistle or other signalling device, and that either the dingy or the larger vessel should follow the diver's bubbles on the surface. Finally, it is a must that buddy pairs stay together at all times, and in fact some operators insist that divers dive in a group of at least four. To become separated from your dive boat this far from land would surely be a disaster.