Cray Cave sits on the outer, south-eastern face of Julian Rocks, the most exposed and current-affected quarter of the island, and is accordingly the domain of more experienced divers. The cave itself is a swim-through narrower and tighter than the well-known Cod Hole a short distance away, threading through the rock at around 18 m before the terrain drops further to a sandy bottom near 25 m, and it takes its name from the painted crayfish that shelter in its recesses year-round. From May to October this is one of the more reliable places at Julian Rocks to find grey nurse sharks resting in numbers, hovering just inside the cave mouth or along the adjacent wall where the current eases; because the site is more exposed than the Cod Hole, it often holds sharks even when boat traffic and diver numbers have moved the animals off the more popular site.

Close by is Gorgonian Hollow, a large horseshoe-shaped rock formation at around 22 m known for the ghost pipefish that hide among its black coral, and operators frequently combine the two as a single deeper Julian Rocks dive for suitably qualified customers. Wobbegongs, moray eels, bullseyes and turtles round out a typical dive here, alongside occasional bull rays on the sand below. Because Cray Cave sits on the most exposed side of the island, it is also the first site to be cancelled when a south-easterly swell picks up, and even on runnable days there is usually more current and surge here than at the Nursery or Hugo's Trench.

Divers should have solid buoyancy control and be comfortable in an overhead swim-through with some current before booking this site, and should not crowd the cave mouth when sharks are present, since sudden disturbance can push them off the site for the rest of the day.

Both Byron Bay dive operators launch small rigid-hull inflatables directly off the beach: Sundive Byron Bay launches from The Pass at the northern end of Main Beach, and Byron Bay Dive Centre launches from the beach near the Wategos/Clarkes Beach end; check in first at the shopfront in town (Sundive: Shop 8, 9-11 Byron St; Byron Bay Dive Centre: Byron Plaza, 5/90-96 Jonson St), then walk down to the beach for the boat launch briefing. It is a short, often bumpy, beach-launch surf crossing before a 5-10 minute run out to Julian Rocks, so loose gear should be secured. No private-boat ramp serves the rocks directly; private boats normally launch from the Brunswick Heads river mouth or Ballina and run up or down the coast.

Julian Rocks sits fully exposed 2.5 km off Byron Bay, so conditions depend on the swell and wind direction rather than any tide window. Trips are cancelled or moved between the Nursery (sheltered west side) and the more exposed east/south sides depending on swell direction and size; a big easterly or south-easterly swell above about 2 m closes the outer sites but the Nursery can often still run. Visibility is genuinely tide- and current-driven here as warm East Australian Current water and cooler southern water meet around the rocks — it can change from 5 m to 20 m within a single day and even between two dives an hour apart.

Summer (Dec-Mar) is warmest (21-26°C) with the leopard shark aggregation and manta ray sightings; winter (Jun-Aug) is cooler (18-21°C) but usually clearer, with grey nurse sharks and migrating humpback whales visible from the boat. Heavy rain from the Brunswick and Belongil systems can dirty the inshore approach for a day or two but rarely affects the rocks themselves once you are out.

Descend to the cave entrance around 18 m, pass through the narrower swim-through (narrower than the Cod Hole) watching for resting grey nurse sharks and resident painted crayfish, continue to Gorgonian Hollow nearby if conditions allow, then ascend along the outer wall.

Sundive Byron Bay (The Pass) – daily double and triple boat dives; Byron Bay Dive Centre (Wategos/Jonson St) – daily double boat dives, Mon & Thu-Sun.