The Shark's Cathedral - Nab Reef, Mauritius: Pinnacle Diving

Diving The Shark's Cathedral means heading offshore from Trou aux Biches, a journey that itself requires stable weather and calm seas, limiting access mostly to the warmer months. Once on site, you'll drop onto a series of prominent underwater peaks and pinnacles that define the reef structure. These formations are often draped in a dense cover of both hard and soft corals, creating rugged topography that shelters a range of reef life while also attracting larger transient species.

The profile for The Shark's Cathedral typically involves an initial descent to around 14 metres, where the top of the main reef structure begins to reveal itself. From there, the terrain drops to a maximum depth of 22 metres, tracing ledges and crevices along the pinnacles. The site's exposed location means a potential for variable current, which can act as a natural conveyor, bringing through open-water hunters and enhancing the overall pelagic activity.

As you move along the reef, keep an eye on the blue water away from the pinnacles. This is where you're most likely to encounter jacks (Carangidae) and tuna, often in schools, using the reef as a transit point or a hunting ground. The currents here can determine the presence and activity of these larger fish; a moderate flow can bring them closer to the reef structure itself, offering better viewing opportunities as they navigate the relief.

Sharks are a significant draw for this site, hence its name. While encounters are dependent on the day's conditions, the pelagic nature of Nab Reef makes it a reliable spot for them. These aren't typically the resident reef sharks you might find closer to shore; expect to see larger species attracted by the deep water and potential food sources that aggregate around these offshore pinnacles. Your dive plan should account for the possibility of these encounters, maintaining a safe distance while observing their natural behaviour.

The visibility at The Shark's Cathedral is consistently clear, often described as 'crystalline', which is key when you're looking for far-ranging pelagics. This excellent water clarity, combined with the dramatic underwater landscape of peaks and pinacles, provides ample opportunities for wide-angle underwater photography. The intricate coral growth also offers a rich foreground for capturing the passing larger species.