Deep six is one of the best so-called boulder sites of the Similan Islands National Park. This dive site has a depth of around 30 meters and is made up of a collection of boulders that are partially submerged. It often has quite strong current and so is commonly completed as a drift dive by experienced divers. There are many swim throughs near the boulders and there is a large arch that has many swim throughs surrounded by sea fans and whip corals. The scenery is really good and divers will get fantastic views of some of the best topography in the area.

Within the nooks and crannies of the dive site, divers can commonly spot crustaceans and pipefish hiding amongst the corals. The boulders often are home to sea snakes, octopus, and mantis shrimps. Divers can also fund large groupers and sweetlips lurking under the table corals and sometimes under the rocks.

In some of the deeper areas, divers can see white tip reef sharks and blue spotted rays. Occasionally large rays such as manta rays also make an appearance. Some areas of the dive site are protected from the currents, and sometimes leopard sharks can be found in these areas when the current is low.