2Nd Cathedral

Lanai's Second Cathedral is a submerged lava tube formation with a large central cavern, multiple volcanic arches, collapsed ceiling "windows" that send shafts of sunlight into the water, and rock walls and ceilings often encrusted with black coral and other sessile invertebrates, creating a dramatic light-and-shadow interior. Divers enter through a large archway and can swim through several smaller chambers and connecting swimthroughs. This is a boat-access-only, guided cavern dive with depths from about 15 ft at the shallow rim to roughly 60-70 ft in the deeper parts. Visibility is generally excellent, often around 100 ft, and water temperatures are typically in the mid-70s to high-70s °F. Currents are usually mild outside the caverns but surge can occur in shallow overhead areas when surface conditions are rough; maintain good buoyancy and be aware of ceilings. Guides may restrict exploration of the highest entrances on windy or wavy days, and advanced open-water certification with cavern or cave experience is recommended. Dives commonly finish on a nearby reef slope or coral garden before surfacing at the boat.