Coral reefs and marine life around Praslin and La Digue

What kinds of coral reef surround Praslin and La Digue?

Praslin and La Digue are granitic islands, and the reefs around them are fringing reefs, granite rock reefs and patch reefs rather than atolls. Nature Seychelles says fringing reefs are characteristic of the granitic islands, with the largest on Mahé and Praslin.

Scientists who have surveyed 21 inner-island reefs since 1994 group them into three habitats: carbonate fringing reefs, granitic rocky reefs and patch reefs. SeyVillas notes that granite rocks form the base of most dive sites around Praslin. Nature Seychelles counts more than 170 species of stony coral in Seychelles and 71 octocorals, such as sea fans.

Not every beach has a reef in front of it. SeyVillas says Anse Source d'Argent is sheltered by a coral reef and Anse Sévère by rock and coral formations, while Grand Anse on La Digue has no offshore reef.

What happened to the reefs in 1998 and 2016?

Marine heatwaves in 1998 and 2016 killed much of the coral around the inner islands. The 1998 event removed more than 90% of live coral cover, and 2016 caused a second large loss.

Nature Seychelles says the 1998 El Niño, combined with the Indian Ocean Dipole, killed over 90% of live coral, and many reefs collapsed into rubble that algae later covered. Around Cousin Island a large area became dead coral rubble. On the long-term survey reefs, average coral cover fell from 25% in 1994 to 7.5% by 2005 (Graham et al., 2024). An earlier study found that as the dead coral broke down, some fish species disappeared locally (Graham et al., 2006).

The 2016 heatwave brought at least as much heat stress as 1998, and probably more, and average coral cover on the survey reefs fell to 6% by 2017. Sources put the scale differently: Nature Seychelles gives a further 50% loss, while the survey recorded recovered reefs falling from 27% cover in 2014 to 8% in 2017.

Have the reefs recovered?

Partly. After 1998 roughly half the surveyed reefs regrew their coral and the rest became seaweed-dominated, and recovery after 2016 has been faster.

Of 21 inner-island reefs, 12 recovered towards their earlier coral cover and nine shifted to fleshy macroalgae. Recovery was more likely on structurally complex reefs in deeper water, with more juvenile corals and plant-eating fish and low nutrient levels; being inside a no-take reserve made no difference (Graham et al., 2015).

After 2016 the recovering reefs reached an average 15% coral cover by 2022. A patch reef off south-west Praslin that had turned to macroalgae after 1998 is shifting back to coral, with 17% coral cover and no macroalgae in 2022. Reefs on both sides of Cousine Island, a separate island from Cousin, went from 2.5% coral cover seven years after 1998 to 39% in 2022 (Graham et al., 2024).

Nature Seychelles' Reef Rescuers project began restoring coral in 2010, transplanting nursery-grown corals across more than 5,000 m² of degraded reef in the Cousin Island Special Reserve. A joint project with Constance Lemuria, funded in 2011, transplanted 2,015 corals over 1,636 m² at Anse Kerlan on Praslin.

Which reef fish and sharks will you see?

Seychelles waters hold more than 1,000 fish species, according to Nature Seychelles. Parrotfish dominate the plant-eating fish on the inner-island reefs, and snappers, fusiliers and barracuda turn up on dive sites around Praslin.

Surveys show parrotfish such as Chlorurus sordidus, Scarus niger and Scarus rubroviolaceus dominate herbivore biomass on both recovering and seaweed-dominated reefs, while the rabbitfish Siganus sutor became one of the main plant-eaters by weight on seaweed-dominated reefs by 2014 (Graham et al., 2024).

SeyVillas describes shoals at St Pierre to 12 metres, snappers and fusiliers at White Reef, batfish, barracuda, octopus and lobsters at Ave Maria, and lionfish at Booby Rock near Aride. It says the Coco Island reef holds many coral fish species.

SeyVillas reports grey reef sharks at Sister Reef, South Marianne and Booby Rock, and whitetip reef sharks at Aride Reef and Channel Rock. Azzura Dive Center on La Digue says shark incidents in Seychelles are extremely rare; never corner or handle one.

Where can you see rays, turtles and whale sharks?

Rays and turtles turn up on many reefs near Praslin and La Digue. Whale sharks are seasonal visitors, usually from about August to November, and no source promises a sighting.

• Rays: SeyVillas says eagle rays are often seen at Channel Rock, between Praslin and La Digue, and at Booby Rock and South Marianne, with stingrays at Sister Reef, Ave Maria and Booby Rock. Azzura notes stingrays often rest in sand or seagrass.
• Turtles: Nature Seychelles says Cousin Island is the most important nesting site in the western Indian Ocean for the hawksbill turtle, which the IUCN Red List classes as Critically Endangered. Turtles also nest on Curieuse, where SPGA runs a seasonal, controlled Nesting Sea Turtle Trail from October to early March, and SPGA calls the hawksbill the biggest attraction of Ile Cocos.
• Whale sharks: SPGA says they can be spotted around Ile Cocos from around August to November. The Marine Conservation Society Seychelles (MCSS) says the main gathering is usually off Mahé's west coast between August and November, and that whale sharks have been protected in Seychelles since 2003. SeyVillas names Channel Rock for whale sharks in "summer and autumn", without giving months.

Which marine parks protect the reefs?

Curieuse Marine National Park, Ile Cocos Marine National Park and Cousin Island Special Reserve protect the reefs most visitors reach from Praslin and La Digue.

• Curieuse Marine National Park, designated on 11 June 1979, covers Curieuse and the channel to Praslin, including St Pierre and Chauve Souris. Its 1979 designation order runs the southern boundary along Praslin's north coast from Pointe Zanquilles past Anse Possession and Anse Boudin to Pointe Chevalier. SPGA names Coral Gardens and Pointe Rouge off Curieuse as dive sites and describes St Pierre as good for snorkelling and diving.
• Ile Cocos Marine National Park covers 85.55 hectares: Ile Cocos, Ile La Fouche, Ilot Plate and Anse Peniche on Félicité, about 7 km from La Digue. It has been protected since 1996, and SPGA calls it the most renowned snorkelling spot in the archipelago.
• Cousin Island Special Reserve, 2 km off Praslin, protects the island and 400 metres of sea around it (Nature Seychelles).

Entry fees change: check current amounts on this guide's Curieuse, St Pierre, Coco Island and Cousin pages, or with SPGA and Nature Seychelles.

Where to snorkel, and when is the sea calmest?

From the shore, SeyVillas recommends Anse Lazio and Anse Boudin on Praslin and Anse Sévère, Anse Source d'Argent and Anse Gaulettes on La Digue. By boat, the usual choices are St Pierre and Ile Cocos. The calmest water usually comes between the monsoons, though sources disagree on exact months.

• Praslin: SeyVillas names Anse Lazio and Anse Boudin as the best shore snorkelling.
• La Digue: SeyVillas lists Anse Sévère, Anse Source d'Argent and Anse Gaulettes, and rates Anse Source d'Argent best at high tide, because at low tide the water is too shallow to swim easily. The Tourism Board describes calm seas at Anse Patates, on La Digue's northern tip. Avoid Grand Anse: SeyVillas says the sea there is choppy, especially in the south-east trade winds, and the currents can carry you out to sea.

Seasons. Azzura Dive Center puts the north-west monsoon at November to March, with heavy rain and choppy seas broken by calm spells, and visibility that can pass 30 metres. The south-east monsoon, June to September, brings cooler, plankton-rich water that can cut visibility to a few metres. Azzura names February to April and October to December as the best diving months. SeyVillas gives north-west trade winds from December to March, south-east trade winds from May to early October with rougher sea and lower visibility, and April and November, with no trade wind, as the best months for snorkelling.

Azzura warns of strong currents at several snorkelling sites: ask your hotel about conditions, never snorkel alone and leave the water before sunset.

What are the rules in the marine parks?

In SPGA's marine national parks you may not fish, carry fishing gear or spear guns, or take shells, plants, coral or other marine life. Boats must anchor in designated areas.

SPGA's rules also ban water-skiing, speedboat racing and other motorised water sports, and littering, and ask visitors to respect all marine life. Access to the northern coast of Curieuse, including Anse Badamier, is prohibited. Azzura Dive Center asks divers to keep neutral buoyancy and not touch marine life, and tells snorkellers and divers not to touch, stand on or get close to hazardous species.

How do you avoid sea urchin and stonefish injuries?

Wear reef shoes, avoid standing on the reef and watch where you step. If a sea urchin spine or stonefish sting gets you, Azzura Dive Center's first-aid advice is to soak the area in hot water for at least 30 minutes and remove any spines carefully.

• Sea urchins live on reefs and seagrass beds, can be well camouflaged, and their spines lodge in skin. Azzura advises hot water for at least 30 minutes, removing any spines carefully without breaking them, and notes that antibiotics may be needed if infection is suspected.
• Stonefish and scorpionfish are hard to spot. Venom from a gland at the base of their dorsal fin spines can be extremely painful. Azzura advises very hot water for at least 30 minutes to break down the venom, and careful removal of any spines.
• Stingrays: shuffle your feet in shallow water so resting rays move away. If stung, Azzura advises removing any barb and soaking the area in hot water for 30 minutes.
• Fire coral and Portuguese man o' war jellyfish (more common in the south-east monsoon) both sting: Azzura advises flushing with vinegar for at least 30 seconds.

For a serious allergic reaction to a sting, Azzura advises getting medical attention as soon as possible.