Green Island tide times

Green Island (Lyudao) sits 33 km east of Taitung in the Philippine Sea, a volcanic fragment roughly 16 km² in area with a coral fringing reef that encircles almost the entire coastline. The island is small enough to circumnavigate by scooter in 45 minutes on the single ring road (13 km), and the combination of clear Pacific water, healthy fringing reef, and the non-trivial distance from the mainland has produced diving and snorkelling conditions that rank among the best accessible from Taiwan.

The tidal regime at Green Island is semidiurnal, Pacific-driven, with a spring range of approximately 1.8 to 2.2 m — slightly smaller than the Taitung coast 33 km to the west and consistent with the open Philippine Sea tidal pattern. Two near-equal highs and two near-equal lows per day. The island sits in the path of the Kuroshio Current, which runs northward through the Bashi Channel and along the eastern side of Taiwan; current speeds around the island can reach 1 to 1.5 knots in the main flow, and the interaction of tidal current and Kuroshio produces variable flow patterns around the island's headlands that require local knowledge or guide awareness.

Zhaori Hot Spring (Zhaori Wenquan) on the eastern coast is one of only three known saltwater hot springs in the world. The thermal water (around 50 to 60°C at the source) emerges on the beach and in shallow rock pools at the sea's edge. The pools are engineered concrete basins positioned at the waterline. At low water on a spring tide, the pools sit above sea level and hold their thermal water without ocean intrusion — the most comfortable and temperature-stable bathing condition. At high spring water, the pools are partially or fully submerged by the sea, and the cold ocean water mixes in and cools the bathing temperature significantly. The productive bathing window at Zhaori is therefore centred on the three to four hours around the predicted low — specifically low water ±1.5 to 2 hours on a day when the range is 1.5 m or more.

The Lyudao Human Rights Memorial Park occupies the site of the former Green Island Prison — the facility used by the Kuomintang government during the White Terror period (1949 to 1987) to hold political prisoners, dissidents, and those accused of communist sympathies. The park is now a designated national memorial site and museum; it is one of the most significant human rights historical sites in Taiwan's recent history and draws visitors independently of the island's natural attractions. The park is at the northern tip of the island, about 2 km from the main Lyudao ferry pier.

Diving at Green Island uses the coral reef perimeter as its primary site structure. Visibility on calm days reaches 15 to 25 m; the reef wall on the eastern and southern sides drops steeply into deep water. The dive window is most comfortable at slack tide and the early incoming flood, when current through the reef channels is minimal. The Kuroshio flow on the eastern side of the island can produce unexpected drift on open dives; using a dive guide familiar with the local current patterns is recommended for first-time visitors, particularly on the more exposed sites on the eastern reef wall.

The island's single ring road takes roughly 45 minutes to circumnavigate by scooter at a relaxed pace. Scooter rental is available at the pier and at the main accommodation cluster near Lyudao village. The road passes all major sites including the Zhaori Hot Spring, the Human Rights Memorial Park, and the reef-access entry points used by the dive operators. No significant road section is affected by tidal conditions.

Predictions on this page come from Open-Meteo Marine, a gridded global ocean model; accuracy is typically within plus or minus 45 minutes on timing and 0.2 to 0.3 m on height. The Taiwan Central Weather Bureau (CWB) publishes authoritative harmonic tide predictions for Taiwan's offshore islands.