Koh Tao tide times

Predictions: Open-Meteo Marine (MeteoFrance SMOC, 0.08° grid) — heights relative to MSL (not chart datum / LAT). Model-derived.

Model-derived from a global ocean grid. Useful indication; expect about ±45 minutes on average vs. a local harmonic gauge, individual stations vary widely. See /methodology for per-region detail. Not for navigation.

Conditions as of 05:00 local time. Refreshes daily.

Predictions: Open-Meteo Marine (MeteoFrance SMOC, 0.08° grid) — heights relative to MSL (not chart datum / LAT). Model-derived. · Not for navigation.

The angler tradition for major/minor fishing windows: major ≈3-hour windows around moon transit and opposition; minor ≈2-hour windows around moonrise and moonset. Times are Asia/Bangkok local. Folk tradition, not a scientific forecast.

Koh Tao is the smallest and most northerly of the three main islands in the Samui archipelago, 40 km north of Koh Pha-ngan and 80 km east of the Chumphon coast. The island is 8 km long and 3 km wide at its widest, shaped roughly like a teardrop with the bay of Mae Haad — the main pier — indenting the west coast. Koh Tao has become the most concentrated scuba diving learning environment in Southeast Asia; over 60 dive schools operate on the island and offer Open Water certification courses year-round. The dive site infrastructure is genuinely extensive: Chumphon Pinnacle (12 km NW), Southwest Pinnacle, Sail Rock (halfway to Ko Pha-ngan), Shark Island at the south tip, and more than 20 named sites in the shallower waters around the island itself. The tidal signal at Koh Tao is the smallest of the three main islands. The further north in the Gulf of Thailand, the weaker the tidal amplitude becomes, because the Gulf's semi-enclosed basin geometry means the tidal wave decays over the propagation distance from the south. Mean spring range at Koh Tao is 0.4 to 0.8 m; neap range in the Gulf summer months can drop to 0.2 m or less. At that amplitude, the tidal state has negligible bearing on beach width, pier access, or boat operations. What the tidal cycle does produce, even with this modest range, is a directional current around the island's rocky headlands and between the offshore pinnacles. Current at Chumphon Pinnacle and the Twins site can reach 0.5–1.0 knots on a spring ebb; the dive guides time drift dives to the current direction, not to the height of the tide. The pinnacles themselves rise from 30–40 m depth; the dive at Chumphon Pinnacle starts at the shallowest point at 14 m and goes down to 36 m on the main structure. Sail Rock is a seamount with a vertical swim-through chimney — a passage from 18 m to 5 m inside the rock — and halocline layers where freshwater mixing creates visibility distortion. Visibility at the Koh Tao sites varies seasonally: November through April (NE monsoon season) brings the clearest water — typically 20–30 m at the offshore pinnacles — as the northeast wind keeps the coast stable and particulate matter settles. May through October visibility drops at some shallow sites as the SW monsoon stirs the water, though the offshore pinnacles and Sail Rock maintain 15–25 m even in SW monsoon periods. The west coast bay of Koh Nang Yuan — three small islands connected by sandbars, accessible by a 10-minute longtail from Mae Haad — is the most photographed scene on the island. The sandbar connecting the islands is fully exposed at low tide and partially submerged at high tide; the walk across the bar is possible during the two to three hours either side of the predicted low. With the modest tidal range, the window is generous: even at mid-tide the bar has only 0.2–0.3 m of water over it, manageable for most waders. Shore anglers work the rocky southern coast near Shark Island and the headlands east of Mae Haad; mackerel and trevally follow the tidal current around the rocky points. The angler tradition that uses moon transits to rate fishing windows scores full-moon and new-moon spring periods more highly — the solunar tradition, applied here, aligns with the slightly stronger current produced by spring tides. Tide predictions are from Open-Meteo Marine, a gridded global ocean model, accurate to ±45 min / ±0.2–0.3 m. For a tidal range this small, that uncertainty is comparable to the signal itself. Thai Meteorological Department (TMD) tables remain the authoritative reference for Thai waters.