Most of the diving gear shops in Krabi are located in Ao Nang.
There are a lot of agencies who operate tours based in Ao Nang. There are two well known places in Krabi where underwater sight seeing is popular. Koh Po Da Nock , otherwise called Chicken Island is one of them which is hardly half an away.
At Koh Po Da Nock, underwater caves are visited by divers. There is one cave which is about 60 metres long.
But the most famous location for underwater sight seeing is the Koh Phi Phi island area which is some 3 hrs away by boat. The tour is arranged from Ao Nang. Under water coral reef various species of colorful fish are seen in this area.
No where in the world is as simple as that in Phi Phi Island as far as snorkeling is concerned. Simply snatch a pair of goggles and paddles. You can move into the shallow waters. Then the mystery of underwater life is clearly visible in the emerald green sea.
There is one ship wreck also in this vicinity. The ship was a local passenger ship from Phuket which sank along with 600 of the passengers a few years back, of course with no casualties. Divers can now see the wreck on the sea bed.
A group of German divers manage an outfit called Poseidon Dive Center. But for the heavy monsoon season from June to August, they are always in service.