Le fer à cheval
17.8802°S 149.2027°W · cave
Le Fer à Cheval (“The Horseshoe”) is an exceptional and rare dive site in the south of Tahiti Iti (the smaller peninsula of Tahiti), located in the area between Teahupoo and Tautira. The site is a submerged lava tube — a large natural tunnel carved through volcanic rock — approximately 100 metres long and 20–30 metres wide, shaped like a horseshoe. It is organised monthly by specialist operators when conditions permit.
Overview
Le Fer à Cheval is one of French Polynesia’s most distinctive dive experiences — an underwater traverse through a volcanic tunnel system rather than a conventional reef or wall dive. The tunnel’s interior features chimneys, a prominent peak known as Oti Point, and near-constant crystal clarity. The site lies within Tahiti Iti’s southern diving frontier, accessible via Tahiti Iti Diving, which also conducts scientific partnership dives; a March 2013 census with IRD (Institut de Recherche pour le Développement) studied Polynesian sponge populations inside the cave system.
Marine Life
The tunnel walls and ceiling are colonised by sponges in significant variety, studied in scientific census work. Prawns, lanternfish, and invertebrates adapted to low-light environments inhabit the tunnel’s interior. On the ocean-facing exit of the tunnel, whitetip reef sharks have been recorded resting on the sand, and heteroconger (garden) eels and pipefish have been observed in the channel. The 200-metre route through the tunnel system yields diverse encrusting life throughout.
Dive Profile
The lava tube runs approximately 100 metres in length and 20–30 metres in width. Depth inside the tunnel reaches up to 25 metres. The site is organised monthly by Tahiti Iti Diving and requires appropriate conditions for safe passage — it is not always accessible. Divers traverse the horseshoe-shaped tunnel and emerge on the ocean side. A specialty or cave diving background, or at minimum an Intermediate open-water certification with strong buoyancy control, is recommended.
Safety Considerations
This is an overhead environment requiring proper buoyancy, torch, and dive experience appropriate for confined spaces. The site is operated only in suitable conditions by Tahiti Iti Diving. Divers should not attempt this site without local guide accompaniment.
Site Information
- Location: Tahiti Iti (Taiarapu Est), Tahiti, French Polynesia
- Entry Type: Boat dive
- Site Type: Cave/cavern
- Difficulty Level: Intermediate
- Maximum Depth: 25 meters
Additional Resources
- Last Updated: 2026-05-17
Sources: Tahiti Iti Diving – Scuba Diving, Tahiti Tourisme – Tahiti Iti Diving. Last updated 2026-05-17.
Sea-surface temperature and wave height from Open-Meteo Marine (ERA5 reanalysis, monthly averages).
157 verified species observations (101 species) logged within ~11 km of this site between 1849 and 2025, from the Ocean Biodiversity Information System.
- Megaptera novaeangliae · Humpback whale
- Gygis alba microrhyncha
- Sula sula · Red-footed booby
- Odontanthias tapui
- Elasmobranchii · Cartilaginous fishes
- Sulidae
- Anous
- Procellariidae · Fulmars / petrels / shearwaters
- Phaethon lepturus · White-tailed tropicbird
- Laridae · Gulls
- Stenella longirostris · Spinner dolphin
- Cheloniidae · Sea turtles
Scientific survey records skew toward sampled taxa (molluscs, corals) and do not reflect what you are guaranteed to see on a dive.
Source: OBIS (obis.org), aggregated Darwin Core occurrence records.
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