Chimney

Overview

The Chimney is a celebrated dive site located along the south coast of Mauritius, renowned for its striking natural rock formation that gives the site its evocative name. A near-vertical shaft cut through the reef allows divers to descend or ascend through a narrow cylindrical passage, emerging into open water with a sense of awe rarely matched elsewhere on the island. The site typically ranges from around 15 to 28 metres in depth, making it suitable for intermediate to advanced divers who are comfortable with confined passages and variable conditions.

The south coast of Mauritius is known for its wilder, more exposed character compared to the calmer lagoons of the north and west. Sites like the Chimney reward divers willing to venture further, offering encounters with pristine coral ecosystems and pelagic visitors that seldom appear in more sheltered waters. The dramatic underwater topography here is shaped by ancient volcanic activity, creating an intricate network of tunnels, arches, and swim-throughs of which the Chimney is the undisputed highlight.

Marine Life

The walls of the Chimney are encrusted with a dazzling variety of hard and soft corals, sponges, and sea fans, providing habitat for an extraordinary range of marine species. As you descend or rise through the passage, keep a keen eye on the surrounding rock for resting nurse sharks, moray eels threading through crevices, and colourful lionfish hovering motionlessly in the shadows.

• Reef fish: Snappers, groupers, parrotfish, and butterflyfish are abundant in and around the formation.
• Sharks: Whitetip reef sharks and occasional blacktip reef sharks patrol the surrounding reef, particularly at depth.
• Turtles: Green and hawksbill turtles are frequently spotted grazing on the reef top.
• Invertebrates: Nudibranchs, feather stars, and spiny lobsters are hidden gems for macro enthusiasts.
• Pelagics: Blue-water species including tuna, barracuda, and trevally sometimes sweep past the outer reef edge.

The biodiversity here is a testament to the health of Mauritius's southern reef systems, which benefit from reduced coastal development pressures compared to other parts of the island.

Conditions

The Chimney presents conditions that vary considerably depending on the season and prevailing weather systems. The south coast is exposed to the southeast trade winds and can experience stronger swells and surface chop, particularly between May and September. Currents at this site can range from gentle to moderate, and divers should always plan their entry and exit carefully with their dive guide.

Visibility at the Chimney is typically excellent, often reaching 20 to 30 metres on calm days, allowing full appreciation of the formation's scale and the surrounding reef. Water temperatures hover between 23°C in the austral winter (July–September) and 28°C during summer (December–March), so a 3mm wetsuit is comfortable year-round, with some divers opting for a 5mm in cooler months.

Best Season

The optimal time to dive the Chimney is during the Mauritian summer, from October through to April, when the southeast trades ease and sea conditions on the south coast become calmer and more predictable. January and February can bring cyclone activity, so it is worth monitoring weather forecasts. However, the winter months (May–September) can still deliver excellent dives on calm days and often bring clearer water and greater pelagic activity.

Tips for Divers

• Always dive with a local guide familiar with the Chimney's specific tidal and current patterns.
• Maintain excellent buoyancy control before attempting the passage to avoid disturbing the delicate coral walls.
• A torch or dive light is highly recommended to illuminate the richly coloured invertebrates within the chimney itself.
• Check conditions the morning of your dive — the south coast can change quickly, and surface support is essential.
• Book through a PADI or SSI-certified dive centre in the south of Mauritius, such as those based in Blue Bay or Mahébourg, for the safest experience.
• Underwater photography here is outstanding — wide-angle lenses capture the scale of the formation beautifully.

Getting There

The Chimney is accessible by boat from dive operators based in the south of Mauritius, including those in Mahébourg, Blue Bay, and surrounding areas. Boat transfers typically take 15 to 30 minutes depending on the departure point. It is not accessible from shore and should only be attempted as part of an organised dive excursion.