Koh Tao · Thailand · Pinnacle · Pelagic & blue water
Sail Rock
A vertical chimney inside the rock, from 18 m up to 6 m
Photo: (WT-en) Titofan at English Wikivoyage · Public domain
A granite pinnacle standing alone in open water roughly between Koh Tao and Koh Samui, Hin Bai rises from the sandy seabed to 15 m above the surface and runs to 40 m below it. The draw is the Chimney, a vertical swim-through inside the rock entered at 18 m, and the barracuda, jacks and whale sharks that gather around the pinnacle in moderate to strong current.
Also known as Hin Bai.
Where it is and how deep
9.9449° N, 99.9904° EApproximate position — the dashed circle shows where the site lies; your operator's briefing has the mooring.
The dive
The pinnacle is the whole site: one iceberg-shaped granite mass standing 15 m above the water and running down to sand at 40 m. Current is moderate to strong, so the circuit is worked with the rock within arm's reach and which face of the pinnacle gives shelter depends on the way the water is moving that day. Visibility is usually in the 10 to 30 m range.
The Chimney is the feature divers come for: a vertical shaft inside the rock on the north-west side, entered at about 18 m and exiting between 12 and 6 m. It is a short, enclosed ascent through the pinnacle itself, taken one behind another, after which groups carry on round the outside of the rock. Buoyancy has to be settled before going in, and anyone not comfortable in an overhead stays outside on the granite.
Out in the blue, barracuda and jacks hold around the pinnacle with batfish closer to the granite, and whale sharks are among the animals listed for the site. The ascent is easier to manage than on the submerged pinnacles off Koh Tao: this rock runs all the way to the surface, so the safety stop is made against it rather than hanging in open water, and the boat has a fixed mark to come back to.
Marine life and season
- Barracuda
- Trevally & jacks
- Whale sharks
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Good | Good | Prime | Prime | Prime | Good | Good | Good | Good | Fair | Fair | Good |
Season follows Koh Tao: No official closure; whale shark sightings peak March-May and September-October, while October-November bring more rain and surface chop.
Know before you go
- Current runs moderate to strong and can change during the dive; work the circuit up-current first and keep the pinnacle within reach as shelter.
- The Chimney is an enclosed vertical shaft with one entry at 18 m and exits at 12 to 6 m: go through in single file with settled buoyancy, or stay outside on the rock.
Photos from Sail Rock
portioid · CC BY 4.0
portioid · CC BY-SA 4.0
portioid · CC BY-SA 4.0
Dive videos
Sail Rock Koh Tao - SCUBA DIVING - Best Dive Site in Gulf of Thailand (near Koh Samui) · Retired Working For You on YouTube
Diving Sail Rock, Koh Phangan, Thailand - 4K · Matt Baer vdomatt on YouTube
Questions divers ask
How deep is Sail Rock?+
The pinnacle breaks the surface and stands 15 m above it, and drops to about 40 m on sand below. The Chimney swim-through is entered at 18 m and exits between 12 and 6 m, so most of the dive sits well above the maximum.
Where is Sail Rock and how do you dive it?+
Hin Bai sits in open water roughly between Koh Tao and Koh Samui and is dived from both. From Koh Tao it is a long boat run, made as a weekly scheduled trip rather than one of the daily departures.
Sources
- Diving in Thailand — Wikivoyage
- Ko Tao — Wikivoyage
- List of deepest dive sites in the Gulf of Thailand — Wikipedia
- Hin Bai (Sail Rock) — OpenStreetMap
Photo credits
- Dive boats anchored beside the granite pinnacle of Sail Rock by (WT-en) Titofan at English Wikivoyage, Public domain, via Wikimedia Commons
- Spotted coral grouper resting on colourful encrusted rock by portioid, CC BY 4.0, via Wikimedia Commons
- Pickhandle barracuda school hanging in blue water off the pinnacle by portioid, CC BY-SA 4.0, via Wikimedia Commons
- Barracuda and grouper over the reef at Sail Rock by portioid, CC BY-SA 4.0, via Wikimedia Commons
In The Logbook
- Where to dive with whale sharks, month by monthBig animals · 16 min read
More dive sites in Koh Tao
Offshore granite tower where barracuda and jacks school in the blue
Drift
Drift over the Nang Yuan rock, with 40 m a short swim west
Reef
Sheltered fringing reef, sandy bottom at 12 m
Pinnacle
Coral-covered pinnacles beside the Sattakut, 7 m to 22 m
44.9 m navy attack craft, mast at 13 m, seabed at 23 m
Upright navy wreck, superstructure at 18 m, keel at 30 m
Reef
Calm reef in the lee of Koh Nang Yuan, 2 to 16 m
Artificial reef
Sunken jeep and scrap at 10 to 12 m, colonised by reef fish
Similar dives elsewhere
Occasional whale sharks and manta over a 45 m pinnacle
A current-swept pinnacle from 30 m to within 5 m of the surface
Mantas and a swirling barracuda vortex over a current-swept plateau
Seamount summit 2 m under the surface, coated in soft coral