The Seychelles’ inner islands are the world’s only oceanic islands formed from granite, remnants of the supercontinent Gondwana that date back over 600 million years. That ancient geology doesn’t stop at the shoreline — it continues beneath the waves, where house-sized boulders create a submerged landscape of arches, tunnels, and swim-throughs softened by coral and sea fans. With 81 catalogued dive sites spanning accessible granitic reefs to expedition-grade atolls, the archipelago offers far more than a beach holiday.
Over 30% of Seychelles’ ocean territory is designated as protected areas — among the highest percentages of any nation on Earth.
Most visitors see Seychelles from the sand, but the real depth is underwater. The inner islands offer some of the easiest shore snorkelling in the Indian Ocean, while a liveaboard to Aldabra Atoll delivers world-class diving that rivals anywhere on the planet. You don’t need a certification to experience the reefs — but if you are certified, you’ll find sites that reward every level of experience.
First-timers
Families
Experienced divers
The table below gives a quick overview of five very different underwater experiences — from a calm lagoon you can enter with just a mask to a remote atoll that requires a dedicated expedition.
| Site | Type | Depth | Skill Level | Best Time |
|---|---|---|---|---|
| Anse Source d’Argent | Snorkelling | Shallow | Beginner / Family | Year-round |
| St. Pierre | Dive | 10 m | Beginner | Apr–May, Oct–Nov |
| Ave Maria Rocks | Dive | 12–20 m | Intermediate | Apr–May, Oct–Nov |
| Shark Bank | Dive | 30 m | Advanced | Apr–May, Oct–Nov (whale sharks Sep–Nov) |
| Aldabra Atoll | Dive / Expedition | Variable | Experienced | Feb–Apr, Oct–Dec |
Inner Islands: Snorkelling Straight from the Beach
The granitic inner islands — Mahé, Praslin, La Digue — offer the most accessible entry into Seychelles’ underwater world. You don’t need a boat or a certification; many of the best reef areas are reachable with just a mask, fins, and a few steps from the sand.
On La Digue, Anse Source d’Argent is the classic example. Parrotfish, angelfish, and butterflyfish weave through soft corals just offshore. On Praslin, Anse Lazio offers a similar experience with slightly deeper water and occasional sea turtles grazing on the seagrass. Curieuse Island, a short boat ride from Praslin, combines clear waters with protected reef status, so the fish populations are noticeably healthier.
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For a guided experience, snorkelling tours in Sainte Anne Marine Park take you to multiple reefs around Moyenne and Cerf islands, where the calmer waters and abundant fish make for easy, rewarding snorkelling.
Diving the Granite Cathedrals
For certified divers, the inner islands reveal a different dimension. The same granite boulders that shape the coastline continue underwater, forming pinnacles, arches, and overhangs that shelter an extraordinary density of marine life. St. Pierre, a tiny islet off Praslin, is a favourite for beginners: you’re almost guaranteed to see hawksbill turtles and blacktip reef sharks cruising the granite grooves.
A short boat ride from Praslin, Ave Maria Rocks drops to 12–20 metres across a series of granite boulders draped in soft corals. The site is known for its reef fish density — schools of fusiliers and snappers — and the occasional nurse shark resting beneath a ledge. It’s a good next step for divers who’ve logged a few dives since certification. BHS Safari’s guide to Seychelles dive sites notes that Ave Maria is suitable for recently certified divers depending on conditions and guide advice.
Granite formations are delicate — soft corals and sponges take years to regrow. Maintain excellent buoyancy control and avoid touching anything. Most dive centres on Mahé and Praslin require proof of certification before taking you to sites below 18 metres.
Advanced Adventures: Current-Swept Pinnacles
For every calm lagoon, there’s a current-swept seamount. Shark Bank, between Mahé and Silhouette Island, is the inner islands’ premier pelagic site. A granite pinnacle rising from 60 metres to 18 metres, it attracts schooling hammerheads between April and October, along with giant trevally and eagle rays. This is a blue-water dive with open-ocean energy — strong currents and deeper depths make it one for confident divers only. Underwater Atlas ranks Shark Bank among the world’s Top 500 dive sites, noting its granite structure and regular visits by whale sharks, grey reef sharks, and large schools of trevally.
Brissare Rocks, north of Mahé, offers a similar experience on a smaller scale. Walls of orange and yellow soft coral cling to the granite, and manta rays pass through during the plankton-rich months of the southeast monsoon (May–October).
Both Shark Bank and Brissare Rocks experience strong currents. Dive operators plan around conditions, but you should be comfortable with drift diving. Advanced Open Water certification is typically required. Recompression chambers are available on Mahé and Silhouette, but conservative dive planning is advised.
The Outer Islands: Expedition-Grade Diving
If you can stretch your budget and time, the outer islands offer something entirely different. Aldabra Atoll, a UNESCO World Heritage Site, is one of the most pristine marine ecosystems on the planet. Its isolation — 400 kilometres from Mahé — has preserved coral health and pelagic populations at densities the inner islands cannot match. Grey reef sharks, hammerheads, and giant tortoises (the atoll is home to over 150,000) define the experience. Access requires a liveaboard expedition of 7–10 days, departing from Mahé.
Alphonse Island, operated by Blue Safari Seychelles, offers a more accessible outer-island experience. Guests at Alphonse Island Lodge can snorkel and dive over thriving coral reefs, join turtle patrols with the Island Conservation Society, or try world-class fly fishing in untouched waters. No liveaboard is needed — charter flights from Mahé get you there in under an hour.
Marine Life You’re Likely to See
You don’t need a liveaboard to see a hawksbill turtle — they’re common on inner island reefs year-round. Snorkellers at Anse Source d’Argent or Anse Lazio often spot them grazing on algae or resting under granite overhangs. Green turtles are also present, and both species nest on Seychelles beaches, with Bird Island running a turtle research programme that allows guests to observe nesting or hatching in season.
Whale sharks are seasonal. Between October and February, they pass through the waters around Sainte Anne Marine Park off Mahé. Sightings aren’t guaranteed, but several operators run dedicated whale shark trips from Beau Vallon during this window. The sharks are filter feeders, moving slowly through the blue — a calm, mesmerising encounter.
Reef sharks — blacktip and whitetip — are common at sites like St. Pierre and Ave Maria Rocks. Manta rays appear at Brissare Rocks and around the outer islands. The granite reefs also support large moray eels, stingrays, and schools of fusiliers, snappers, and parrotfish.
Whale shark season runs October to February, peaking around November. If seeing one is a priority, plan your trip around this window and book a dedicated whale shark tour from Mahé’s Beau Vallon Bay.
Planning Your Underwater Adventure
Getting the most out of Seychelles’ underwater world comes down to timing, logistics, and choosing the right sites for your skill level.
Mahé has the widest choice of dive operators and the easiest access to sites like Shark Bank and Brissare Rocks. Praslin is better for St. Pierre and Ave Maria, and La Digue gives you the best shore snorkelling at Anse Source d’Argent. Most visitors split time between two islands. A day trip from Mahé to Praslin is feasible if you’re short on time.
Beginner divers and snorkellers should stick to St. Pierre, Whale Rock, and the sheltered lagoons of La Digue and Praslin. Intermediate divers can handle Ave Maria Rocks and Conception. Advanced divers should target Shark Bank, Brissare Rocks, and South Marianne. Outer island expeditions suit experienced divers comfortable with liveaboard conditions.
Choose dive centres that are licensed and experienced with local conditions. Many operators on Mahé and Praslin offer equipment rental, PADI courses, and guided dives. For outer islands, private island getaways often include guided snorkelling and diving as part of the package.
Water temperature sits at 26–30°C year-round, so a 3mm wetsuit is standard. Bring reef-safe sunscreen, a hat, and your own mask and fins if you have them — rental quality varies. Underwater cameras are worth the space; the granite backdrops and clear water (visibility often 30–40 metres in peak season) create excellent photo conditions.
The best diving conditions across the archipelago occur in April–May and October–November, when seas are calmest and visibility peaks at 30–40 metres. The southeast monsoon (May–October) brings rougher water to exposed coasts but attracts whale sharks and plankton feeders. Year-round, the northwest monsoon (November–April) favours west-facing beaches.
Before You Dive: Seychelles Underwater FAQ
Do I need a diving certification to see the reefs?
No. Snorkelling at Anse Source d’Argent, Anse Lazio, and Sainte Anne Marine Park requires only a mask, fins, and snorkel. Many shallow reef areas are accessible from the beach. If you want to dive, several operators offer introductory “discovery” dives for uncertified guests.
What’s the best time for calm seas and good visibility?
April to May and October to November are the calmest windows, with underwater visibility often reaching 30–40 metres. These months also offer settled weather for island-hopping. The southeast monsoon (June–August) brings cooler water and plankton, which can reduce visibility but attracts whale sharks.
When can I see whale sharks?
Whale shark encounters are most likely between October and February, particularly around Sainte Anne Marine Park off Mahé. Sightings are not guaranteed, but dedicated trips from Beau Vallon Bay offer the best chance. The sharks are filter feeders and move slowly, making for a calm encounter.
Are there beginner-friendly dive sites?
Yes. St. Pierre off Praslin maxes out at 10 metres with mild currents — ideal for recently certified divers. Whale Rock (also Praslin) offers similar conditions with archways and swim-throughs. Fisherman’s Cove Reef on Mahé is another shallow option with light current.
What about strong currents?
Sites like Shark Bank, Brissare Rocks, and South Marianne Island are known for strong currents and require advanced certification. Dive operators monitor conditions daily and will not take groups to sites that exceed their skill level. Always follow the dive master’s briefing.
Beyond the Beach
The granite boulders that make Seychelles’ beaches so iconic continue beneath the waves, creating a world that’s as ancient as it is vibrant. Whether you snorkel from a La Digue beach or descend into the blue at Shark Bank, the archipelago’s real depth is underwater. For a different perspective on the submerged landscape, explore Seychelles’ wreck dives, where sunken ships have become artificial reefs teeming with life.
References
BHS Safari. “Journal Seychelles Diving Snorkelling Reef Guid.” BHS-Safari.co, 2025. ↗
Underwater Atlas. “Seychelles Dive Guide.” UnderwaterAtlas.com, 2025. ↗
Crest Africa. “Seychelles Coral Reefs Travel Guide.” CrestAfrica.com, 2025. ↗
For more on Seychelles’ marine life and conservation efforts, check out the giant tortoise encounters on Bird Island, or plan a windsurfing and kitesurfing trip to make the most of the trade winds.
Explore Places to Stay in Seychelles
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