Giant Tortoises and Coral Reefs of Astove

Astove Atoll sits 1,000 kilometres southwest of Mahé, closer to the coast of Madagascar than to the Seychelles capital. Its narrow ring of land — in places only a few dozen metres wide — wraps around a 21-square-kilometre lagoon, forming a sliver of terrestrial life between the sky and the open Indian Ocean.

Two plane rides from Mahé, this outer atoll sees so few visitors that its coconut groves and coral gardens remain in the condition they’ve been in for centuries. This article covers what makes Astove worth the journey: the giant tortoises that roam its interior, the reef wall that plunges into deep water, and the practical realities of getting here.

The Atoll — Landscape and Layers

Astove’s shoreline is a study in contrasts. On the lagoon side, sand flats stretch smooth as mother-of-pearl, reflecting the sky in pale tones. On the ocean side, fossilised coral formations called champignons rise in sharp, jagged shapes that tear at skin and boats alike. The atoll’s thin land border — just enough to support a dense stand of coconut palms — separates these two worlds.

The most visible landmark on the northwesterly shore is the wreck of the Shangri-La, a yacht whose past is unknown. It’s one of several vessels that have come to grief here; Astove’s reef has claimed ships seeking harbour since the 16th century. According to local legend, the Portuguese frigate La Dom Royal sank off the atoll in 1760. The crew made for Mozambique by longboat, leaving behind a group of enslaved people who lived freely on the island for 35 years, the reef dashing every attempt to recapture them.

The atoll also bears the marks of a more recent human presence. British adventurer Mark Veevers-Carter established a coconut plantation here in 1968; he died two years later. His former home now serves as Astove Coral House, the atoll’s first guesthouse, which opened shortly before the pandemic.

Giant Tortoises — Aldabra’s Outliers

The same reef that once dashed ships now protects one of the Indian Ocean’s most remarkable reptile populations. Aldabra giant tortoises — the same species that numbers more than 150,000 on nearby Aldabra Atoll — roam freely through Astove’s interior, grazing on fallen coconuts and sheltering under the palm canopy.

Aldabra, a UNESCO World Heritage Site since 1982, hosts the world’s largest population of these tortoises, which can reach 250 kilograms and live more than a century. The Aldabra Group — which includes Astove and Cosmoledo — was saved from the fate of most other Indian Ocean islands by its isolation. In the 19th century, sailors hunted giant tortoises to extinction on island after island; Aldabra’s remote position and treacherous reef kept the hunters away.

Conservationists have since moved some tortoises to other islands as a hedge against extinction. On Cousin Island, a recent study led by Seychelloise researcher Alessia Lavigne at the University of Sheffield examined why Aldabra giant tortoises have such low hatching success in the wild. The team found that 75% of undeveloped eggs had been fertilised but contained embryos that died early — suggesting environmental factors, not genetics, drive the failure rate. Thirteen hatchlings were produced in the first successful artificial incubation of the species, offering a potential lifeline if wild reproduction continues to falter.

On Astove, the tortoises you’ll see are part of this broader Aldabra population — survivors of a lineage that persisted through human expansion largely because the places they lived were too hard to reach.

The Coral Reef — A Vertical World

What does it feel like to float above a 900-metre drop? The reef wall on Astove’s ocean side is one of the steepest in the Indian Ocean — a vertical coral garden that plunges from sunlit shallows into almost a mile of darkness. Jacques Cousteau filmed parts of his 1956 documentary The Silent World here, pioneering underwater colour photography in these same waters.

Snorkelling the reef wall reveals battalions of bluestripe snapper and Napoleon wrasse among roughly 1,000 species that pass through this living corridor. Tiny fish twitch in synchronised patterns, and larger species — giant trevally, groupers, reef sharks — glide through the deeper water. The scale is hard to absorb: the reef face is layered with coral formations that change colour and composition as the light fades, and the sense of open ocean below is constant.

The wider picture for Seychelles’ reefs is sobering. The Seychelles Conservation and Climate Adaptation Trust (SeyCCAT) released the Status and Trend of Seychelles Coral Reefs: 2026 report in May 2026, drawing on 3,778 observations across 285 sites over 32 years. For the Aldabra Group — which includes Astove — coral cover showed steady recovery through 2023 before a sharp decline to roughly 14% in 2024, driven by the most severe thermal-stress year in the available record. The 2024 event was part of the Fourth Global Coral Bleaching Event, which scientists warn could lead to the loss of 90% of the world’s coral by 2050 if current trends continue.

Astove’s reef remains one of the least-explored dive sites globally — a function of its remoteness rather than any special resilience. The same isolation that protects the tortoises has kept the reef relatively undisturbed by direct human impact, but it cannot shield it from rising water temperatures.

Visiting Astove — One Guesthouse, Two Plane Rides

Getting to Astove takes two plane rides and a deliberate decision to leave the mapped world behind. The first flight — from Mahé to Alphonse Island on a 16-seat Beechcraft jet — covers 400 kilometres south. From Alphonse, a second, smaller plane continues southwest to Astove. The total journey takes the better part of a day.

Astove Coral House is the atoll’s only accommodation: a four-bedroom guesthouse converted from Mark Veevers-Carter’s former plantation home. It operates under Blue Safari, the same company that runs Alphonse Island Lodge and Cosmoledo Eco Camp. The setup is barefoot eco-resort — solar power, desalinated water, meals built around what can be flown in or grown locally. There’s no overwater bungalow, no spa, no multiple restaurants.

Activities revolve around the reef and the lagoon. Fly-fishers stand in the shallows all day catching and releasing giant trevally. Snorkelers explore the reef wall with a guide. Those who simply want to walk the atoll can trace the shoreline from the Shangri-La wreck to the old plantation paths, crossing paths with tortoises and hermit crabs along the way.

The atoll’s extreme isolation means very few people ever see it. Blue Safari and adventure operator Reefscape Travel offer multi-day packages that bundle flights, accommodation, meals, and guided activities. Independent travel to Astove is not feasible — there are no scheduled flights and no public accommodation.

Note: The research does not provide current per-night pricing for Astove Coral House. Contact Blue Safari directly or check their website for the latest all-inclusive rates and available dates.

Planning Your Visit to Astove

You don’t show up at Astove on a whim. The atoll’s remoteness is its defining feature, and it shapes every part of a visit — from how you book to what you pack.

Access and Booking

All visits to Astove go through Blue Safari or a partner operator like Reefscape Travel. Packages include inter-island flights from Mahé, accommodation at Astove Coral House, all meals, and guided activities. The research does not specify exact lead times, but given the single guesthouse and limited flight capacity, booking several months ahead is reasonable. Check Blue Safari’s site for current package options and availability.

When to Go

The southeast trade winds blow strongest from roughly May to October, whipping up the sea and making the ocean-side reef more challenging for snorkelling. The calmer months — November to April — offer flatter seas and better conditions on the reef wall. However, these are also the hotter months, with higher UV exposure and the risk of marine heat spikes. The research does not give exact monthly breakdowns for Astove specifically; confirm conditions with Blue Safari when booking.

What to Bring

Reef-safe sunscreen is essential — the Seychelles has strict regulations on sunscreens containing chemicals that harm coral. Sturdy water shoes are equally important: the champignons (fossilised coral) along the shore and on the reef flat can cut feet badly. Snorkel gear is provided by the guesthouse, but if you have your own mask and fins, bring them. There is no shop on the atoll, so anything you forget stays forgotten.

Conservation Context

Astove sits within the Aldabra Group, part of the Seychelles’ Outer Islands managed by the Islands Development Company under a strict “one island, one resort” policy. The atoll falls within the marine protection zone covered by the Seychelles’ 2018 Blue Bond initiative, which raised $15 million from international investors to write down national debt in exchange for protecting 30% of the country’s waters. Astove’s reef and tortoise populations benefit directly from this arrangement — the isolation is legal as well as geographic.

Before You Go — Astove Atoll

How do I get to Astove from Mahé?

Fly from Mahé to Alphonse Island (a 16-seat Beechcraft jet, roughly 400 km south), then take a second, smaller plane southwest to Astove. The full journey takes most of a day. Both flights are included in Blue Safari packages.

Can I dive the reef wall, or is it only for snorkelers?

Certified divers can dive the wall with a guide from Astove Coral House, but it’s an advanced site — strong currents, deep water, and open ocean exposure. Snorkelers stay in the shallower sections near the wall’s top. Either way, you go with a guide who knows the daily conditions.

Will I definitely see giant tortoises?

Yes — they roam the atoll freely and are commonly seen along the old plantation roads and under the coconut palms. They’re most active in the cooler morning hours. The research does not report a specific count for Astove, but the Aldabra population exceeds 150,000, and Astove’s tortoises are part of that broader group.

What is the single biggest downside of visiting Astove?

The remoteness cuts both ways. If weather grounds the small plane, you could be stuck on the atoll for extra days. The guesthouse has limited supplies and no medical facility beyond basic first aid. Travel insurance that covers medical evacuation from the Outer Islands is strongly recommended.

A Reef and a Refuge

Astove remains what it is because so few people reach it. The same factors that make the journey difficult — distance, wind, a reef that has sunk ships for centuries — are the ones that keep the tortoises grazing under the palms and the coral growing in water that still holds species Cousteau filmed seventy years ago. It’s not a place you visit casually. But for the traveller willing to trade convenience for one of the Indian Ocean’s last genuinely raw atoll experiences, Astove delivers something increasingly hard to find: a place where nature still sets the terms.

If Astove’s blend of remote wildlife and pristine reef appeals to you, explore our guide to Seychelles environmental conservation efforts for more on how the country protects its Outer Islands, or read about Seychelles’ most secluded beaches for other hard-to-reach coastal escapes.

References

Blue Safari. “Astove Coral House.” ↗

Barret, L. and Gendron, G. “Status and Trend of Seychelles Coral Reefs: 2026.” Seychelles Conservation and Climate Adaptation Trust (SeyCCAT), 2026. ↗

Reefscape Travel. “Outer Islands Trips.” ↗

For a deeper look at the Outer Islands’ conservation model, read our piece on Seychelles environmental conservation. If you’re planning a broader Seychelles trip, our guide to Praslin’s hidden mangrove forests covers a very different kind of island ecosystem, and photographing Seychelles’ landscapes offers tips for capturing the granite islands that contrast so sharply with Astove’s flat coral ring.