A drift dive on the north side of Koh Nang Yuan, named for the green cast the rock takes on near the surface. The main dive runs between 10 and 25 m, with 30 to 40 m a short swim to the west for divers with the training for it. Titan triggerfish and white-eyed morays are common, and the rock is a regular stop for macro photographers.
Where it is and how deep
10.1255° N, 99.8110° EPublished position for this site.
The dive
Groups drop on the north side of Koh Nang Yuan and let the water carry them across the rock, which is what earns the site its drift label. Most of the dive sits between 10 and 25 m over broken rock. The rock nearest the surface looks green through the water, and that is where the name comes from. A short swim west of the main structure puts you on deeper ground, 30 to 40 m, which is a planned leg for divers with deep training rather than somewhere to drift into by accident.
Titan triggerfish hold territory on the rock and white-eyed moray eels sit in the cracks, both common enough that guides expect to find them. Green Rock is also a nudibranch dive, specifically recommended for divers who want to photograph macro life, which means the 10 to 25 m section rewards a slow pass over a small piece of the structure rather than a lap of the whole thing. Finish shallow over the green-tinged rock, where the drift eases and the safety stop is simple to hold.
Marine life and season
- Nudibranchs
| 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.
Questions divers ask
Why is it called Green Rock?+
The rock closest to the surface looks green through the water, and the site takes its name from that. It sits on the north side of Koh Nang Yuan, next to Koh Tao.
Sources
- Green Rock - Scubago — Scubago
More dive sites in Koh Tao
Offshore granite tower where barracuda and jacks school in the blue
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
Reef
Plateau and canyon off the headland, sponges from 8 to 18 m
Similar dives elsewhere
Strong-current ridge with soft coral gardens and big boulders
Three huge rocks with coral slopes, quieter than East of Eden
A granite drift with blacktip and whitetip reef sharks
Fast drift over a rocky slope with devil rays and reef sharks