Siaes Hammer
Dive site
Siaes Hammer is a T-shaped reef projection that juts into open water from the outer reef wall southwest of the Rock Islands, creating a natural aggregation point for schooling hammerhead sharks between January and April. Divers descend to a plateau at 25 meters where the hammer-head reef creates an upwelling, and small schools of scalloped hammerheads — sometimes dozens strong — circle overhead before dispersing into the blue. The wall below the plateau drops sheer to 300 meters and is draped in black coral and large gorgonian fans. Outside hammerhead season the site still delivers grey reef sharks, silvertip sharks, large dogtooth tuna, and occasional thresher sharks ascending from depth.
Conditions
Depth
10 to 40 m
Advanced depths
Current
Usually gentle
Can pick up on the edge
Visibility
20 to 38 m
Clearest in the calm season
Water
27 to 30°C
3mm wetsuit
Month by month
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Water (°C) | 27 | 27 | 27 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 27 |
| Vis (m) | 25 | 25 | 25 | 25 | 22 | 20 | 18 | 18 | 18 | 20 | 22 | 22 |
| Current | Moderate | Moderate | Moderate | Moderate | Gentle | Gentle | Moderate | Moderate | Moderate | Gentle | Moderate | Moderate |
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