Fish Rock Cave
Julian Rocks · Australia
Only true ocean cave dive in Australia — a 125 metre tunnel that punches straight through a rocky islet two kilometres southeast of Smoky Cape. The deep entrance opens at 24 m and the cave climbs through a chimney to a sunlit shallow chamber at 12 m, the so called Aquarium, fringed in pink gorgonian fans. Critically endangered grey nurse sharks aggregate around the rock all year, peaking from May through September when dozens stack in the deep gutters and rest at the cave mouth. Schooling hammerheads pass through from October to January. Resident black cod, wobbegongs, and giant cuttlefish work the walls; bull rays and turtles cruise the sand.
Conditions
Depth
12 to 30 m
Open water and up
Current
Usually gentle
Can pick up on the edge
Visibility
20 to 30 m
Clearest in the calm season
Water
17 to 25°C
7 mm wetsuit
Month by month
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Water (°C) | 23 | 23 | 22 | 21 | 19 | 18 | 17 | 17 | 18 | 19 | 20 | 22 |
| Vis (m) | 10 | 10 | 15 | 15 | 20 | 20 | 20 | 20 | 20 | 15 | 15 | 10 |
| Current | Moderate | Moderate | Moderate | Gentle | Gentle | Gentle | Gentle | Gentle | Gentle | Moderate | Moderate | Moderate |
Your chances of seeing each animal
Grey nurse shark
Last confirmed May 15, 2026 · 130 records
Almost always
Nearly every dive
Black cod
Last confirmed May 18, 2025 · 8 records
Very likely
Most dives
Green turtle
Last confirmed Jun 13, 2026 · 8 records
Very likely
Most dives
Bull ray
Last confirmed Aug 18, 2024 · 1 records
Likely
About 6 in 10 dives
Tasselled wobbegong
Expected
Known here, not yet in recent logs
Giant cuttlefish
Expected
Known here, not yet in recent logs
Scalloped hammerhead
Expected
Known here, not yet in recent logs
Gear
Basic kit
For this site
- Primary dive light · The mid section of the cave between the chimney and the deep entrance is fully dark.
- Backup torch · Mandatory for the through cave traverse; light failure inside the tunnel means turning the dive.
- Reef hook or SMB · Currents around the rock can pick up sharply and surface marker buoys are essential for the open water ascent off the wall.
- 7 mm wetsuit · Peak grey nurse season sits between 17 and 20 C with long bottom times in the cave.