Mariner's Cave

No surface marker — the entrance is 2–3m down on the west wall, with a swim of roughly 3–4m through the tunnel before you can surface inside. The only light is blue, coming back through the entrance. The breath-hold entry is the part people underestimate; go with a guide who knows the tunnel and the swell.

Depth

2–17m

Current

Mild

Diver level

Advanced open water

Entry

Boat

Unique features

Air-filled chamber entered through a submerged tunnel on Nuapapu Island
Swell compresses the air inside, fogging the chamber and clearing it again with each surge
Upper entrance at 2–3m for breath-hold swimmers; a second entrance around 16.5m for divers

Sources & last checked

Checked July 2026

This is a researched draft, not yet human-verified. The seasonality and logistics are drawn from the sources below — confirm specifics (permits, fees, closures) with an operator before you book.

Diving Mariner's Cave - Vava'u Tonga — SV Soggy Paws
The Best Scuba Diving in Vava'u — Tonga Pocket Guide

Note on the data: Coordinates are approximate; not surveyed dive-site GPS.