Hin Wong Bay Dive Site, Koh Tao: Sharks & Snorkelling

Hin Wong Bay is a large, horseshoe-shaped bay on the rugged east side of Koh Tao, with Hin Wong Pier close by. Dive trips taxi to the pier and take a shuttle to the dive boat, roughly 15 to 20 minutes, and the bay is often combined with Hin Wong Pinnacle or Lighthouse Bay.

It is a quiet, uncrowded corner of the island. Granite boulders line the shoreline and merge with coral, and further out the bay opens into a gentle reef slope with big coral bommies and sandy channels. Blacktip reef sharks are the star, though how often you see them depends on the time of year.

Hin Wong Bay dive site map

1Shoreline boulders
2Shallow coral garden, 4 to 6 m
3North side crevices, 5 to 14 m
4South corner swim-through
5South boulders, snorkel zone
6Coral bommies, 8 to 16 m
7Sandy channels ~16 m

Usual route: Boat entry on the outer bay, then drift in over the bommies to the shallow coral garden, passing the crevice-rich north side or gentler south side before finishing in the shallows. Drawing based on local dive briefings: approximate, not to scale and not for navigation. Your guide's briefing on the day always comes first.

Diving Hin Wong Bay: the route

The boat enters on the outer bay, and you drift in over the bommies to the shallow coral garden. From there you can follow the crevice-rich north side or the gentler south side, and finish in the shallows.

Depths run from about 2 to 20 m, with most dives staying in the teens. It is a good fit for Open Water divers and for Advanced Open Water and refresher dives.

Hin Wong Bay is also used for Open Water course dives, which says a lot about its overall character. The terrain is varied enough to stay interesting, but the depth is friendly, so you can concentrate on buoyancy around the granite and enjoy the fish.

Underwater layout

The bay is a horseshoe open to the east. A shallow coral garden at 4 to 6 m leads into slightly deeper rocky ground with granite boulders, bommies, sandy channels and open sand. It drops to roughly 14 m on the outer edges and about 20 m at the maximum. Hard coral covers the shallows, and the bigger rock formations lie deeper.

The south side is gentler and has a swim-through cave in one corner, which makes it the best part of the bay for snorkelling. The north side is a more cracked and rocky maze of crevices, where yellow boxfish and visiting sea snakes shelter. Hin Wong Pinnacle lies about 1.5 km offshore.

Marine life at Hin Wong Bay

Blacktip reef sharks are the reason many divers choose this bay, and they are reported in good numbers almost daily at certain times of year. Ask your guide what the recent sightings have been like. Fusiliers and snapper hang in mid-water, trevally and queenfish patrol the edges, moray eels tuck into the granite and blue-spotted stingrays rest on the sand.

Common: fusiliers, snapper, rabbitfish, parrotfish, sergeant majors, moray eels, blue-spotted stingrays, Jenkins whiprays, butterflyfish and blue-ringed angelfish.
Now and then: blacktip reef sharks, sea snakes, turtles, and barracuda in deeper water.
Macro: yellow boxfish, nudibranchs and mantis shrimp.

Hard corals dominate the shallows, and the shoreline boulders are fused with coral in places. Granite fused with coral forms little pockets where small fish and critters shelter, so it rewards a slow pace and a close look at the rock.

Snorkelling at Hin Wong Bay

The south side is the place to snorkel. It is gentler, with granite boulders close to the surface and the swim-through in the corner. Keep to the calmer days, as the east side is exposed in the monsoon.

Conditions and best time to dive

The bay is usually calm, though a light to moderate current can come through with the tides. Visibility varies a lot, from around 2 to 10 m on a poor day to 10 to 25 m on a good one, so it is worth asking your guide about conditions.

June to September is best, when the south-west monsoon shelters the east coast. October to December, during the north-east monsoon, is the time to avoid.

If the bay is clear it can be a lovely dive, and if it is murky the sharks and the structure still make it worth a look. Compared with the pinnacle offshore, the bay is calmer, shallower and more forgiving, though its visibility swings more.

Tips from local divers

Ask about blacktip shark sightings, they depend on the season.
Check the visibility before you book, it varies more here than at the pinnacle.
Explore the north-side crevices slowly for boxfish and sea snakes.
Practise good buoyancy around the granite.

Safety notes

Visibility can be poor on some days, and the terrain is rocky, so careful buoyancy matters. Sea snakes visit the bay. They are not aggressive, but keep your distance and do not touch them.