St John's Island tide times

St John's Island — Pulau Sakijang Bendera in Malay — sits approximately 6.5 kilometres south of the Singapore mainland, a 15-minute ferry ride from Marina South Pier. The island covers 39 hectares and carries a complicated administrative history: it served as a quarantine station for immigrants in the 19th century, an internment camp during World War II, a detention centre for political detainees in the 1960s and 1970s, and a drug rehabilitation centre before its current use as a leisure island and aquaculture research facility. The Marine Aquaculture Centre, run by Singapore Food Agency, occupies the southeastern portion of the island and conducts research into sea bass, snapper, and grouper breeding — a visible reminder that Singapore takes food security seriously even at 6.5 kilometres offshore.

The ferry jetty on the northern side dries at extreme low water springs. Spring tidal range in the Strait of Singapore is approximately 2.7 metres, and the tidal regime is mixed semidiurnal with a pronounced diurnal inequality. At the lowest low waters — which occur roughly twice monthly on spring tides — the outer jetty pilings are exposed to the waterline and the approach channel carries less than 0.5 metres of water. The ferry schedule is adjusted for this, but visitors arriving by private boat should check the day's tide table before timing their approach.

The Sisters' Islands Marine Park, comprising Big Sister (Pulau Subar Laut) and Little Sister (Pulau Subar Darat), lies 300 metres southwest of St John's and is administratively part of the same southern island cluster. The two islands together with St John's and Lazarus Island form a connected group at low water springs when the inter-tidal platforms linking them become partly walkable. Coral restoration nurseries maintained by the Marine Conservation Group operate in 3 to 5 metres of water between the islands — the nursery frames are visible from the surface when water clarity is good, which is highest on incoming tides when cleaner Strait water replaces the turbid water draining off the reef flats.

For anglers, the deep water on the southern and western faces of St John's — the sides exposed to the Strait of Singapore — holds grouper, snapper, and trevally in 10 to 25 metres. The flood tide is consistently the productive window, when fish move inshore along the reef drop-off to feed on invertebrates mobilised by the rising water. Squid jigging from the jetty on calm evenings around high water produces good results in the cooler months (November to February).

The southern recreational beach is sheltered from the main shipping lane and has calm water suitable for swimming at any tide state above half-tide. The lagoon between St John's and Lazarus Island is similarly protected and shallow enough for snorkelling on a rising tide when water clarity improves. Lazarus Island is connected to St John's by a constructed causeway passable on foot at all tide states.

Ferry services from Marina South Pier run several times daily; check the Sentosa island ferry schedule for current timings. The crossing takes approximately 25 minutes to St John's, with some services continuing to Sisters' Islands and Kusu Island. Demand is highest on weekends and public holidays. The island has a holiday camp facility managed by Singapore Land Authority, several sheltered picnic areas, and a lagoon swimming enclosure with lifeguard cover on weekends.

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 metres on height — model-derived, not from a local gauge. The local tide authority is the Maritime and Port Authority of Singapore (MPA), which publishes annual tide tables for Singapore Strait reference stations.