Swallows Cave 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 17:00 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 Pacific/Tongatapu local. Folk tradition, not a scientific forecast.

Next spring tide on Wed 20 May (range 1.2m). Next neap on Sat 23 May.

Spring tides cluster around new and full moons (biggest swings). Neap tides land on quarter moons (smallest swings). See the spring tide and neap tide glossary entries for the why.

Swallows Cave is a sea cave on the eastern coast of Kapa Island in the Vava'u Group, approximately 4 kilometres north of Neiafu. The cave is accessible by boat at any tide level — the entrance is at the waterline, approximately 8 metres wide and 3 metres high at the arch, opening into a cavern roughly 30 metres deep and 20 metres wide. The cave's name comes from the Pacific swallows (Hirundo tahitica) that nest on the cave walls and ceiling year-round, exiting in formation at dawn and returning at dusk. The daily flight of the swallow colony — dozens of birds streaming out through the cave entrance at first light — is one of the distinctive natural events of the Vava'u Group. The cave interior holds a still pool of seawater that reflects the filtered light entering through the main arch. At certain times of day — mid-morning when the sun angle is low enough to send light directly through the arch into the cave interior — the pool surface glows blue-green with refracted light. The effect lasts for approximately 45 minutes as the sun moves; the window changes with season and time of year. Boat operators familiar with the cave know the optimal time for the light show. Snorkelling inside the cave from the pool surface gives a clear view of the cave walls and the fish community using the cave for shelter. Grouper, snapper, and various reef fish hold in the cave during daylight hours; the transition from the cave's sheltered interior to the open water of the Kapa Island reef face takes 3 to 4 minutes of surface swimming. The cave water clarity is good — the enclosed space receives cleaner water on the incoming tide from the outer Vava'u channels. The tidal range at Swallows Cave follows the Vava'u Group's mixed semidiurnal regime: spring range approximately 1.0 to 1.2 metres. Tidal state affects the cave entrance experience primarily through the water level on the cave pool surface — at high water springs, the water level inside the cave is approximately 0.5 metres higher than at low water springs, which changes the height of the air space inside the cave arch and slightly alters the light refraction pattern. At low water springs, more of the cave walls above the waterline are visible from the pool. Entry by snorkel or standing on the boat platform is possible at all tide states. The boat trip from Neiafu to Swallows Cave takes approximately 20 to 30 minutes, passing through the inner Vava'u channels. The cave is a standard stop on day-boat tours that also include Mariner's Cave and one or more outer island beaches. Most day tours depart Neiafu by 09:00. Photographers should plan for the mid-morning light-through-arch window. A waterproof camera or a housed camera provides the best results inside the cave — the interior is dim except during the light window, requiring ISO 800 to 1600 and a wide aperture if shooting handheld. The dawn swallow flight, captured from a boat positioned outside the cave entrance at first light, requires early departure from Neiafu (05:30 to 06:00). 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 Tonga Meteorological Service.