Katedrala is Premuda's signature underwater cave system in the bay of Siroka, built around a domed chamber linked to smaller caverns and tunnel-like passages. Light pours through openings in the roof, creating the site's well-known cathedral effect. It suits trained scuba divers who want a guided cave-style dive with careful buoyancy and a torch. The cave walls and outer edges hold sponges, corals, wrasse, crabs, octopus, and larger schooling fish.