Prison Island Wall
Cocos (Keeling) Islands · Australia
The southern lagoon wall near the historic Prison Island drops sharply from the reef flat into deep water, sheltering a diverse community of reef fish alongside steady shark traffic. The wall is notably colourful with encrusting sponges and soft corals, and resident turtles rest in the larger cavities. This is one of the more sheltered sites in the atoll and accessible in moderate wind conditions when exposed reef edges are unusable.
Conditions
Depth
8 to 30 m
Open water and up
Current
Usually gentle
Can pick up on the edge
Visibility
20 to 28 m
Clearest in the calm season
Water
26 to 30°C
3mm wetsuit
Month by month
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Water (°C) | 28 | 28 | 28 | 28 | 27 | 26 | 26 | 26 | 27 | 27 | 28 | 28 |
| Vis (m) | 15 | 15 | 18 | 20 | 20 | 20 | 20 | 20 | 20 | 18 | 16 | 15 |
| Current | Gentle | Gentle | Gentle | Still | Still | Gentle | Gentle | Gentle | Gentle | Gentle | Gentle | Gentle |
Your chances of seeing each animal
Green Sea Turtle
Last confirmed May 15, 2026 · 20 records
Very likely
Most dives
Bluefin Trevally
Last confirmed Jun 11, 2026 · 26 records
Very likely
Most dives
Grey Reef Shark
Last confirmed Oct 14, 2025 · 8 records
Very likely
Most dives
Whitetip Reef Shark
Last confirmed Jun 11, 2026 · 12 records
Very likely
Most dives
Red-tooth Triggerfish
Last confirmed Oct 15, 2025 · 1 records
Likely
About 6 in 10 dives
Silvertip Shark
Expected
Known here, not yet in recent logs
Encrusting Sponge
Expected
Known here, not yet in recent logs
Soft Coral
Expected
Known here, not yet in recent logs
Gear