Poor Knights Islands — Rikoriko Cave

Rikoriko is one of the largest sea caves in the world, carved into the volcanic tuff of the Poor Knights Islands Marine Reserve. A cathedral-sized chamber fills with filtered blue light at mid-morning. The walls are dense with golden zoanthids, purple urchins, and the endemic demoiselle. Outside the cave, schooling trevally and kingfish patrol the open water above kelp forests draped in orange and crimson nudibranchs.