The Cathedral

Flic en Flac's signature dive drops down a coral-crusted wall into a vaulted cavern where the site earns its name: light falls through openings in the ceiling in tight, angled beams, and divers hang in a blue-lit nave watching soldierfish and sweepers circulate along the walls. Lobster pack the crevices, morays and scorpionfish hold the ledges, and outside the entrance the wall carries on past sponge-crusted overhangs toward 30 meters. Timing matters (surge amplifies inside on big-swell days and the cavern rewards small groups), but on a clean morning it is the west coast's best hour underwater.

The moment you come for: Light beams inside the cavern; lobster-packed crevices; sculpted wall terrain

Topography: Fringing-slope wall cut by a large cavern, arch, and chimney formations

Current: Generally calm on the leeward west coast; surge reaches the cavern when swell wraps in.

Hazards: Overhead environment in the cavern, surge, and depth at the base of the wall.

Conservation: Fins and gauges scar cavern walls fastest: trim tight in the confined sections.

Nitrox: Worth it here: profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).