Île de Groix & Lorient · France · Wreck
U 171
A German U-boat lost to a mine on its way back to base
The U 171 is a German Second World War submarine lying off Pen Men on Île de Groix, the flagship wreck of the island. The boat struck a mine on its way back to the U-boat base at Keroman, and its hull now rests on the bottom at 38 m, a deep wreck dive for divers trained to Niveau 2.
Also known as U-171, Unterseeboot 171.
Where it is and how deep
47.6500° N, 3.5667° WApproximate position — the dashed circle shows where the site lies; your operator's briefing has the mooring.
The dive
The dive goes down to a German submarine hull resting on the seabed at 38 m off Pen Men, deep enough that it is planned as a Niveau 2 dive. Divers see the U-boat from the outside only: going inside the wreck is formally forbidden, and divers visiting the site are warned of the ban.
The wreck
- Vessel
- U 171
- Type
- German submarine (U-boat)
- Sunk
- 1942
- Cause
- Struck a mine between Lorient and Groix while returning to Keroman
- Lies
- On the bottom at 38 m off Pen Men, Île de Groix
U 171 was a German submarine based at the Lorient U-boat base. On 9 October 1942, on its way back to Keroman, it struck a mine between Lorient and Île de Groix and sank off Pen Men. Today it is the flagship wreck of Groix.
Marine life and season
The sources we used don't single out particular species here.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Fair | Fair | Fair | Good | Good | Good | Prime | Prime | Good | Good | Fair | Fair |
Season follows Île de Groix & Lorient: Boats go out every morning in July and August; the island club's season runs from April to October.
Know before you go
- Penetration of the hull is formally forbidden; the visit stays on the outside of the submarine.
Dive videos
U 171 - île de Groix · Nath dive on YouTube
Sources
- L'île de Groix, spot de plongée — Lorient Bretagne Sud Tourisme
- Unterseeboot 171 — Wikipédia
More dive sites in Île de Groix & Lorient
Wreck
A sunken tug close to Port-Lay, home of the island's dive club
Wreck
A cargo ship turned German blockade-breaker, sunk off the ferry harbour
Similar dives elsewhere
Wreck
Aliah wreck
Glénan Archipelago · France
An overturned bow full of congers on a 1940 Dutch freighter
A coal barge at 30 to 37 m, its coal cargo still in the wreck
A ship lying upside down, its hull facing the surface
Porto Santo's deepest dive, on a cargo boat sunk in 2000