Koh Tao tide times

The tidal range at Koh Tao is small — spring range 0.4–0.8 m, neap range as low as 0.2 m. The height of the tide has almost no practical effect on dive site access or boat operations. What matters for diving is the tidal current: at Chumphon Pinnacle, Southwest Pinnacle, and the Twins, current can reach 0.5–1.0 knots on spring ebb and flood. Dive operators time drift dives to current direction and strength rather than high or low water. The current state at the offshore sites is best judged by local guides with knowledge of the site-specific pattern. Sail Rock (halfway to Ko Pha-ngan) is a seamount exposed to Gulf currents; the swim-through chimney is done on the ascent regardless of current. Visibility is the primary planning variable — November through April is the clearest season.

Yes. Koh Nang Yuan is three small islands connected by white sand bars, accessible by longtail from Mae Haad pier (10 minutes, 100 THB return). The sandbar connecting the northernmost island to the two southern ones is fully exposed at low water; the sandbar between the two southern islands is only exposed at low spring. With a spring range of 0.4–0.8 m at Koh Tao, the tidal window for crossing on foot is generous — even at mid-tide the sandbar sits under only 0.2–0.3 m. Check the predicted low on this page; the walk is comfortable in the two to three hours centred on predicted low water. No diving equipment, plastic bottles, or food are allowed on Koh Nang Yuan — the islands enforce their own conservation rules.

Koh Tao's combination of geography, conditions, and price created a self-reinforcing ecosystem. The underwater topography — sloping sandy bays on the west coast for Open Water training dives, multiple offshore pinnacles with reliably gentle conditions — suits both beginners and advanced divers. Visibility in the NE monsoon season (November–April) averages 20–30 m at the offshore sites. The small tidal range means boats can use fixed moorings rather than tide-adjusted anchoring, simplifying dive logistics. Price competition between 60+ dive schools has driven course costs to among the lowest in the world for a reputable certification. The island infrastructure built around diving — accommodation, transport, equipment rental — reinforces the loop. Water temperature runs 27–30°C year-round.

The NE monsoon season, November through April, is the primary high season. Northeast winds keep the west coast bays calm, visibility at the offshore pinnacles peaks at 20–30 m, and the gulf is at its clearest. March and April are particularly good months: the NE monsoon eases, water is warm (30°C), and crowds thin from the January peak. May marks the transition to the SW monsoon; some west-coast beaches experience minor swell and conditions at shallow sites can deteriorate. June through October is manageable but variable — some dive sites on the west and north close on rougher days, but the offshore pinnacles remain diveable through most of the SW monsoon season. The island never fully closes.

Predictions on this page are from Open-Meteo Marine, a free gridded global ocean model, with typical accuracy of ±45 minutes on timing and ±0.2–0.3 m on height. At Koh Tao, where spring range is 0.4–0.8 m, the model uncertainty can equal a substantial fraction of the actual signal. The tidal state matters less here than at most coastal destinations — what matters more is wind forecast, swell height, and current at specific dive sites. The Thai Meteorological Department (TMD) publishes official tide tables for Thai waters and is the authoritative source. Dive operators on the island have site-specific current knowledge that is more operationally useful than any tide prediction model.