
Admiralty Anchor (Osprey Reef)
Great Barrier Reef · Australia
A wall site on Osprey Reef's western edge named for a centuries old admiralty pattern anchor wedged inside a narrow cave passage at around 20 m. The coral terrace at 8 to 15 m steps off into a vertical wall that vanishes into more than 1,000 m of indigo Coral Sea water. Nutrient rich currents rise against the structure and pull in grey reef and whitetip sharks, schools of midnight snapper, red tail wrasses, and lyretail hogfish; eagle rays and the occasional dwarf nautilus drift past the deeper edges. Visibility routinely tops 60 m and can exceed 80 m from September to November when the trade winds drop.
Conditions
Depth
8 to 35 m
Advanced depths
Current
Can be moderate
Can pick up on the edge
Visibility
30 to 55 m
Clearest in the calm season
Water
24 to 30°C
5mm wetsuit
Month by month
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Water (°C) | 28 | 28 | 27 | 27 | 26 | 25 | 24 | 24 | 25 | 26 | 27 | 28 |
| Vis (m) | 25 | 25 | 30 | 35 | 35 | 30 | 30 | 35 | 40 | 40 | 40 | 30 |
| Current | Gentle | Gentle | Gentle | Gentle | Moderate | Moderate | Moderate | Moderate | Gentle | Gentle | Gentle | Gentle |
Your chances of seeing each animal
Grey reef shark
Last confirmed Nov 15, 2025 · 130 records
Almost always
Nearly every dive
Whitetip reef shark
Last confirmed Jan 25, 2025 · 3 records
Likely
About 6 in 10 dives
Midnight snapper
Expected
Known here, not yet in recent logs
Lyretail hogfish
Expected
Known here, not yet in recent logs
Eagle ray
Expected
Known here, not yet in recent logs
Dwarf nautilus
Expected
Known here, not yet in recent logs
Gear