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Koh Samui Diving Guide

The Best Sites in the Gulf of Thailand

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...Good for: Small animals, beginner divers, value-for-money, snorkelling and non-diving activities
Not so good for: Wrecks and drift dives...

Samui has been welcoming visitors since the early 1970's and has developed into the most popular tourist destination on the east coast of Thailand. The Gulf of Thailand is somewhat sheltered from the major oceans in the region and that protection gives the gulf a number of high quality dive sites which can be visited all year round. Chumphon Pinnacle and Sail Rock are the 2 most famous sites and their popularity with more experienced scuba divers justifiably merits their place at the top of Koh Samui's dive daytrip locations.

Diving in Koh Samui - Orange soft coral tree
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Many pelagic fish such as whale sharks are frequent visitors to the area. There are towering pinnacles, huge rock formations, colourful soft and hard corals, and sloping reefs. Schools of snapper and barracuda abound, and the area is famed for its turtles and triggerfish.

Most of the dive sites in the region are close to the famous island of Koh Tao and can be visited on daytrips out of Samui. Although most people would agree that the scuba diving is better on Thailand's west coast, Koh Samui Island on the east coast still has access to some world class sites.

One popular diving site closer to Samui is Koh Yippon, located in the far north of the Angthong Marine National Park, a picturesque rocky island covered in tropical trees. Once you peer underwater, you will find plenty of beautiful hard and soft corals, sea anemones and purple barrel sponges, all easy to spot in shallow waters, so this location is excellent to combine snorkeling and scuba diving.

While snorkelers are exploring the exciting small caves and crevices in shallow water, divers can enjoy big schools of fusiliers, large snappers or have a glance under the rocks and corals to find Kuhl's stingrays. It's the best place in the Gulf of Thailand to find lionfish and cuttlefish.There are also some big schools of small yellow-tailed barracuda and lots of blue-ringed angelfish.
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Samui's Dive Sites

Click on a twisty ('++' sign) to show more detailed information on each Koh Samui dive site:

++ Sail Rock

Sail Rock is a big granite pinnacle that breaks the sea's surface half way between Koh Phangan and Koh Samui. It is the best dive site in the area as there are no other rocks around so it acts as a congregation point for all the fish in the surrounding area.

The pinnacle drops down to 30 metres in the sand and is typically dived in a circular route around the rock, spiraling slowly shallower. If currents are strong however, divemasters will guide customers around the sheltered areas, avoiding hard finning in the currents. There are other outer rocks a little deeper that can be seen from the main pinnacle and are home to reef sharks.

On a clear day, with light filtering down into the crystal blue water, the granite boulder looks stunning. Enormous schools of trevally are all over the dive site and they energetically harass the smaller fish which bunch together and move as one for protection from these darting raids.

The always-friendly longfin batfish are also often present in great numbers. They may follow scuba divers and curiously peer into your mask, seemingly as interested in you as you are in them. They make wonderful photographic subjects. Whale sharks occasionally cruise by too, especially between February and October, as do other pelagic fish. Always keep an eye on the big blue!

Koh Samui's Sail Rock is best known for its chimney, a large swim-through that is entered at around 20 metres and can be exited in 2 places, first at around 10 metres or shallower at around 5 metres deep. The chimney's cavern-like area is a haven for all sorts of fish life like schools of glassfish that appear to block your exit, only to part at the last second to reveal the holes.

Hingebeak and boxer shrimps inhabit the coral wall. The latter can sometimes be seen cleaning a moray eel's teeth and, with patience, a lucky diver could get a free manicure if they leave their hand still for long enough. Scorpionfish are well camouflaged on Sail Rock's wall so care with buoyancy is required when exiting the chimney. The hole at 10 metres is quite tight so most divers carry on up to the 5 metre exit and are rewarded by a blanket of anemones on the outer side.

Dive The World Thailand Recommendations: Sail Rock.

Diving Season in Samui

You can visit the Koh Samui and Koh Tao diving spots year round, but the very best conditions exist from March to September, which is when the resort areas on the Andaman coast have their low season. During these months you might experience visibility in excess of 30m.

Whale sharks, one of the drawcards of the area, are most frequently spotted in March and April and again in September and October. Other sharks are best seen in the Gulf of Thailand in times of cooler water temperature such as October and December when you might experience seas around 27°C, although that is only a few degrees lower than the annual high of about 30°C.

October to November brings the Northeast monsoon winds and surface swells to the islands, reducing visibility by about 30%. It's pretty rare that any daily dive trips from Koh Samui are cancelled due to bad weather, but speedboat rides can be somewhat bouncy.

It can also be windy and wet in the Gulf from November to February so it may be better to go diving in Phuket, Phi Phi or the Similan Islands then.

Reef Basics

Map of Koh Samui (click to enlarge in a new window)

Depth: 5 - 30m
Visibility: 5 - 30m
Currents: Can be strong
Surface Conditions: Calm to moderate
Water Temperature: 27 - 29°C
Experience Level: Beginner - advanced
Number of dive sites: ~10
Access: Day trips from Koh Samui by speedboat
Recommended length of stay: 1 week


... Vic was very accommodative and helpful with all my questions (which I have a lot). I'm not an easy customer to handle and his help was much appreciated and made the whole booking process such an ease ... , Malaysia