The Lavezzi Islands sit ten kilometres south-east of Bonifacio and from the boat they look like someone scattered a handful of white granite rocks across the sea. No villages, no roads, no houses — only rocks, sandy coves, clear water and a nature reserve under strict protection since 1982. For snorkelling on Corsica, this is the place.

What the Lavezzi are

The Îles Lavezzi are a group of granite islets and rocks in the Strait of Bonifacio, the channel between Corsica and Sardinia. They lie about 4 km off the Corsican coast and 10 km south-east of Bonifacio. The highest point is barely 50 metres; these are islets rather than islands.

The group has a handful of islands:

• Lavezzu (66 ha) — the largest of the reserve islands, where boats land
• Cavallo (112 ha) — the only permanently inhabited island, with a few luxury villas; no public access
• Piana, Ratino, Porraggia, Sperduto — smaller uninhabited islets and rocks

On Lavezzu sits the southernmost point of metropolitan France.

Tip Lavezzu isn't a casual swimming beach. It's a nature reserve with rules: no landing on islands other than Lavezzu, no fires, no camping, no fishing, no taking shells. Surveillance is real and fines are stiff.

Why you go

Snorkelling — this is the main reason. The water around Lavezzi is exceptionally clear, even by Corsican standards, with visibility up to fifteen metres on a good day. The rocks below form labyrinths that schools of fish weave through — look for mussel beds, sea bream, parrotfish and, with luck, an octopus between the rocks. No coral reefs, but a rich Mediterranean fauna.

Sandy coves — scattered across Lavezzu are small bays of fine white sand: Cala di Greco, Cala Lazarina, Cala di u Turcu. Boats land at Cala di Greco or Cala Lazarina; from there you can walk in half an hour to the others.

Granite landscape — walking the island (a loop is 1.5-2 hours) you move between boulders sculpted by wind and sea into bizarre shapes. Some are huge, some perfectly round — a geological open-air museum.

The Sémillante — on the island stands a small cemetery with the graves of victims of the wreck of the French frigate La Sémillante, which went down here in February 1855 during a storm. All 750 on board perished. Two memorials commemorate the disaster. A sober, affecting spot.

Tip Bring your own snorkel mask. Boats sometimes rent them, but quality varies. Your own mask, well-fitting, is the difference between half an hour of clear viewing and an endless fight with leaking water.

The boat trip from Bonifacio

Boats to Lavezzi leave from the harbour of Bonifacio, late March to late October, with several departures a day in July and August.

Two types of tour:

• Half day (4 hours) — direct return to Lavezzi, with a 2-3 hour swim stop on the island. Around €30-40 per person.
• Full day (6-7 hours) — Lavezzi + the cliffs of Bonifacio + sometimes the sea caves Sdragonatu and Saint-Antoine. €45-60 per person.

The crossing to Lavezzu takes around forty minutes, past the white limestone cliffs of Bonifacio and the Strait. On the way the boat passes Capo Pertusato, Corsica's southernmost tip with its lighthouse.

What you need

• Snorkel gear — own mask and snorkel beat rentals. Optionally fins
• Water shoes — the bays have fine sand, but you climb over rocks getting in and out
• Sun protection — there's almost no shade on the island. Hat, longer sleeves or a light sarong help
• Water and food — no shops or restaurants on the island. Pack a lunch
• Sunscreen — minimum SPF 30, reapplied. The wind hides the burn
• Light layer for the boat — the outbound leg is often windy

Tip Want guided snorkelling? Some operators offer a guided snorkel tour that takes you to the best rock formations and points out the marine life. A bit pricier, but worthwhile if you have little snorkel experience.

When

• Best months: June, September. Clear water, calmer sea, fewer people
• Avoid: days with maestrale. The Strait of Bonifacio is one of the windiest spots in the Mediterranean and in a strong north-westerly, boats are either cancelled or simply unpleasant
• Water temperature: rises from 18°C in May to 25°C in August. A rashguard or shorty wetsuit is worth it outside high season

Practical

• Departure point: Quai Comparetti in Bonifacio. Several operators, similar pricing. Book at least a day ahead in July/August
• Sardinia day-trip alternative: from Bonifacio a ferry also runs to Santa Teresa Gallura, an hour each way. No snorkelling, but a day in Italy
• Accessibility: limited — you step from the boat directly onto a rocky landing
• Combine with: a morning in Bonifacio itself, or an evening visit to Capo Pertusato for sunset