Thailand eastern sea ranges from Pattaya Bay, Koh Larn, Koh Sak, Samae San, Koh Mun, Koh Samet to the end of the eastern coastline at Koh Chang. The underwater marine lives are mainly hard corals, Neptune's cup sponge. The good dive sites are situated at Koh Lan, Koh Sak, Samae San while shipwrecks such as Suthatip and Petchburi Bremen are good wreck diving sites.

Chumporn is known for its unique black corals, sea anemones, leather soft corals and rich in marine fishes. The popular diving sites here are Koh Ngam Yai, Koh Ngam Noi and Koh Lak Ngam.
Koh Tao The good dive sites include Kong Chumporn, Kong Tunggu, Hin Bai (Sail Rock), Kong Sai Daeng where divers will find beautiful underwater scenery with hard coral, black corals, sea whips, sea combs, and large schools of reef fishes such as jacks, bat fishes, etc.
Lo Sin consists of outcrops, almost at the far end of Gulf of Thailand and is part of Pattini Province. This outcrop lies outside of the Narathiwat shore by 55 miles. Here are shelters for large numbers of reef fishes such as schools of jacks, white and red snappers, bat fishes and barracudas.
 

Andaman Sea

The Andaman Sea lies in great length along the west coastline of the golden axe. The Andaman coast stretches some 894 kilometers from Ranong Province to Satun Province. The Andaman Sea on this side has clearer and deeper water with more colorful and abundant marine animals than those at the eastern coastline. It becomes famous and known to visitors and scuba divers all over the world.