Shark Island
Depth is the range from the top of the site to its usual maximum; "recommended cert" is the mainstream-agency level operators usually ask for, not a legal rule. Currents and visibility change daily — treat everything here as planning ranges.
The name describes the rock's dorsal-fin profile above water, not a resident population, and guides enjoy clearing that up on the ride over. What the islet actually offers is Koh Tao's most varied single circuit: boulder slopes with dense soft coral and sea whips, gorgonian clusters unusual for the gulf, banded sea kraits threading the shallows, turtles on the sponge ledges, and sandy breaks where blue-spotted rays settle. Angelfish and sweetlips add color the west-coast sites lack. With swell running it turns washing-machine shallow, and on those days everyone learns why the schedule shuffles sites.
The moment you come for: Soft-coral variety, sea kraits and rays, an honest name-myth debunking
Topography: Granite islet with boulder slopes, soft coral, and sand patches
Current: Swell and current wrap the rock when the wind is up; the lee side usually works.
Entry: Off Koh Tao's southeast corner; more exposed than the west-coast sites, so it is a conditions-day call.
Know before you splash
Hazards: Surge and swell exposure; occasional stronger current off the points.
Conservation: Exposed-coast coral recovers slowly from storm and anchor damage; use the moorings and mind surge spacing.
Who you'll meet
Banded Sea Krait
Blue-Spotted Ribbontail Ray
Green Sea Turtle
Nudibranchs
Oriental Sweetlips
For photographers
Wide angle: ★★★★☆ · Macro: ★★★☆☆ — editors' 1–5 rating of what this site gives each style of shooting