What's the difference between diving in the Gulf of Thailand where Samui is located and the Andaman Sea? Dive professionals say waters in the Gulf are shallower and its marine life may not be as rich as that of Similan or Racha islands in the Andaman. Some dive sites around Samui may prove to be as rich and extraordinarily interesting though.

The Gulf has other advantages, too. Gulf water is said to be warmer so divers don't need a wetsuit. Also, Samui, Angthong, Koh Nangyuan, Koh Tao and Koh Phangan are said to be more scenic than their Andaman counterparts.

Koh Tao probably offers the best diving in the Gulf. Located about 41 miles off Samui, Koh Tao's underwater is clear and provides ideal condition for coral growth. Its water depth is perfect for all diving skill levels. For beginners, the shallow and sandy beach areas offer the perfect environment.

What's more, Koh Tao offers year-round diving. There are many sheltered sites on many sides of the island in any given season. Some of the most visited diving is to be had in only about 18 meters, while there are lots of even shallower sites for snorkelers. But a number of rocky pinnacles in the area offer dives as deep as 40 meters as well.

One great thing about Gulf diving is the prospect of seeing large fish species such as barracuda, jacks or groupers, which are native to the Gulf. If you're lucky, you can even encounter shale sharks, rarely sighted anywhere in the world.

Advanced divers prefer Hin Bai or Sail Rock, located north of Samui. The best diving season at Sail Rock is between February and September, when the likelihood of seeing larger sea animals like sharks is high.

The waters around Samui may not be recommended for scuba veterans planning a holiday here. But it is indeed a good base to make your open-water scuba certification. It does have some patches of nice live coral, though, and some species of fish can be spotted as well. The underwater visibility and coral cover off the western sides of Samui are reduced by sediments from the coastal runoff.

The east coast of Chaweng and Lamai beaches, for example, is better. It is fine for instruction or shore-based night dives. But local operators usually go beyond for dive cruises.

Koh Phangan, only an hour from Samui by boat, has some good reefs for snorkeling. The northernmost islands of Angthong National Marine Park also offer some good diving but visibility may be uncertain as the Angthong group of islands is affected by run -off sediments from the large river to the west.

The Gulf of Thailand in general may still be the best underwater destination in Thailand. There's no doubt too it offers some of the best beaches in the country.

Special thanks! for information from "What's on after dark" and "What's on this week"