The Blowhole

Overview

The Blowhole is a distinctive dive site located off the north coast of Mauritius, not far from the iconic Coin de Mire island. It takes its name from a natural volcanic formation where surge and swell funnel through narrow underwater passages, pushing water upward in powerful blasts that mimic the famous surface blowhole phenomenon. The site sits on the outer reef system, where the relatively open Indian Ocean meets Mauritius's fringing reef, creating a wonderfully rich and dynamic environment for divers of all experience levels who are comfortable with mild to moderate current.

The underwater topography here is dramatic. Divers descend past large volcanic boulders and swim through tight channels carved by millennia of wave erosion. The rock faces are encrusted with hard and soft corals, sea fans, and sponges, giving the site a lush, garden-like quality despite its rugged character. Depths typically range from around 12 metres to 25 metres, making it accessible to advanced Open Water divers while still offering plenty for more experienced divers to explore.

Marine Life

The Blowhole's dynamic water movement creates the perfect conditions for filter feeders and the predators that follow them. Divers regularly encounter a rich cross-section of Indo-Pacific reef life throughout the site.

• Reef Fish: Large schools of fusiliers, snapper, and surgeonfish are constant companions. Blue-striped snappers and grouper patrol the deeper sections, while parrotfish and wrasse are abundant along the coral walls.
• Pelagics: The site's proximity to open water means occasional visits from trevally, barracuda, and even eagle rays gliding through the blue. Lucky divers have reported sightings of reef sharks cruising the outer drop-off.
• Invertebrates: Sea fans up to a metre wide provide shelter for longnose hawkfish and pygmy seahorses. Nudibranchs of striking variety cling to the rock surfaces, delighting macro photographers.
• Turtles: Green and hawksbill turtles are frequently spotted resting on the reef or grazing on sea grass patches in the shallower areas.
• Moray Eels: Giant morays peer from crevices throughout the site, alongside whitemouth morays and the occasional snowflake moray in the shallower zones.

Dive Conditions

Conditions at The Blowhole can vary significantly depending on swell, wind, and tidal state. On calm days with light surge, the site is approachable for advanced Open Water divers with good buoyancy skills. When swell is running from the north or east, the surge inside the channels can become quite powerful, and the site is best left to experienced divers comfortable with surge diving techniques. Visibility is generally good, averaging 15–25 metres, though it can be reduced after prolonged winds or heavy rain that stirs up sediment in the lagoon system.

Current is typically mild to moderate, but the channelling effect of the geological formations can accelerate water movement in certain corridors. Divers should always conduct a thorough pre-dive briefing with their guide and avoid entering the tightest passages during strong swell conditions. A surface marker buoy (SMB) is strongly recommended for safety.

Best Season

The best months to dive The Blowhole are from October to April, when the south-east trade winds subside and sea conditions in the north become calm and settled. This period coincides with Mauritius's warm summer season, when water temperatures rise to 27–29°C and visibility peaks. November to February can bring occasional cyclone-related swells, so always check the forecast before diving. The cooler winter months from May to September bring strong south-east winds that can make the north coast choppy, though experienced divers may still find windows of good conditions.

Tips for Diving The Blowhole

• Always dive with a local guide familiar with the surge patterns and tidal cycles at the site.
• Check swell forecasts in advance – even small south-easterly swells can amplify dramatically inside the channels.
• Carry an SMB and deploy it at the start of your ascent; boat traffic can be present on the surface.
• Use a 3mm wetsuit in summer and a 5mm in winter for comfort during longer dives.
• Buoyancy control is critical – avoid touching the coral-encrusted walls inside the passages.
• Macro photographers should focus on the smaller channels and overhangs where nudibranchs and crustaceans congregate away from the surge.