Cathedral Rocks - Rottnest Island snorkelling

Cathedral Rocks, at Rottnest's West End, is one of the island's best-known dive sites. It takes its name from a large limestone cave at the heart of a network of caverns, where weed swaying over holes in the roof sends flickering shafts of light into the water, like sunlight through the windows of a cathedral.

Sponges coat the cavern walls, fish gather in the shade, and grey nurse sharks use the cave as a daytime resting place - usually one or two, and up to a dozen at once. The caves lie 10 metres and more below the surface, inside the West End Demersal Sanctuary Zone, and are calm enough to visit only a few days a year.

Above water, a viewing platform looks over the rocks where New Zealand (long-nosed) fur seals haul out, and for most visitors that is the way to enjoy Cathedral Rocks. Entering the water here is only for very experienced swimmers on an exceptionally calm day.

• Experience level: Advanced
• Depth: 10-26 m at the caves (dive site)
• Access: The caves are a boat dive, normally with a scuba charter; there is no shore entry. The seal viewing platform above the rocks is a short walk from the West End (Island Explorer Stop 11), and the RIA map shows public toilets at Cape Vlamingh. RIA marks a Boating Prohibited Area around the seal rocks. West End swell and strong currents mean the caves can be dived only on a few calm, settled days a year.
• Underwater Caves
• Light Shafts
• Grey Nurse Sharks
• Seal Viewing Platform
• Colourful Sponges
• Sanctuary Zone

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