Diving in the Andamans is a unique lifetime experience. The coastal water surrounding theses islands is the abode of one of the richest coral reef ecosystem is the world. The specialty is that here the coral reefs and underwater formations are undamaged by human activity. The best season for diving is from December to April. Many of the islands are surrounded by fringing reefs, often several hundred meters wide and separated from the shore by a lagoon of similar width. There are also more steeply undulating hills of raven volcanic lava, which makes for some unusual diving. There are plenty of steeply sloping and shallow reefs suitable for snorkeling. Large pelagics are plentiful in these waters, as are a variety of sharks. Large schools of hammerhead often patrol the waters away from the reefs and Grey, Whitetip, Nurse and Leopard sharks are found closer inshore. Silvertip and Ocean Whitetips also sometimes appear out of the deep blue beyond. Enormous manta Rays are also often seen.