Dangerous Reef

The reef can be circled in a single dive when the current allows. Most plans work the sheltered area beneath the southern moorings, where short caverns at 7 to 10 metres are easy to thread. They never reach far into the reef and always lead back out in a semicircle. Just west of the caverns a small, dense coral garden along the wall is a favourite photographer's stop; east of them, large coral rocks sit on the sand hiding their residents. Working north along either the eastern or western wall brings you to the coral garden and towers at the northern tip.

Both walls are equally coral-rich, so guides pick whichever side is in sunlight for the best light. At night the same southern caverns become the area's torch-lit dive, with moray, squid and the occasional Spanish dancer out on the reef. The flow is moderate and the southern anchorage is notably sheltered, which is what makes the reef a relaxed, sociable dive by day and a safe one after dark.

Dangerous Reef trades on a name its own divers disown. It is one of the gentler and more sociable St John's dives, and two things set it apart. The first is that it is the system's night dive of choice: the shallow southern caverns are short, naturally semicircular and easy to exit, which makes them a safe after-dark site. The second is its shape. A 410 metre horseshoe gives good shelter from wind and waves, so it doubles as the natural overnight anchorage at the southern end of the route, and for many trips it is the last and southernmost dive of the safari.

The name has a literal origin. Sharks were once often found sleeping in the caves to the south, and the spot took the label despite posing no special hazard. As of 2025-2026 the wider Deep South is living through a regional bleaching event, so the coral garden is harder to vouch for than older accounts suggest, but the sheltered shape and the night-dive caverns are what bring divers back.

This is a relaxed dive that still rewards care. The southern caverns are short daylight swim-throughs that loop back out, but they are an overhead all the same: stay within natural light, mind your trim, and do not penetrate beyond your certification. Because the reef is a sheltered overnight mooring, it can be busy underwater, especially on the night dive, so carry a torch and watch your spacing. The walls run stronger flow than the moorings, with deeper drop-offs below recreational limits, so pick the lee side in current and plan a maximum depth.

Like all of St John's, this is remote, liveaboard-only diving, dived as the southern bookend of a Deep South safari. The nearest recompression chamber is around 200 kilometres away at Marsa Alam, so dive conservative profiles and carry DAN-style insurance. Nitrox is worth taking for the repetitive multi-dive days.