MFV Bugaled Breizh was a French trawler from Loctudy, Finistère, whose sinking with all hands in 90 metres of water in the English Channel on 15 January 2004 remains unresolved.

[3] Bugaled Breizh capsized with five sailors about 14 nautical miles (26 km) southwest of Lizard Point, Cornwall on 15 January 2004 at 12h25 UTC.

Several hours after the sinking an announcement was made by the French Maritime Prefect for the Atlantic that a NATO naval exercise involving submarines was taking place in the area.

However, according to authorities Dolfijn was at least 15 kilometres (8.1 nmi) away and the Royal Navy indicated as well that its submarines were not at the site where Bugaled Breizh sank.

The report of the French Marine Accident Investigation Office (Bureau d'enquêtes sur les événements de mer or BEAmer) was published on 27 November 2006 and examined a number of possible causes; it rejected the proposition that fishing lines got entangled with a military submarine and concluded that "the hypothesis that the fishing line got buried in a sandbank is more consistent with the evidence.

[14] An analysis of the French Institute of Research for the Exploration of the Ocean subsequently rejected the proposition of BEAmer as impossible.

[16] A recent newspaper article states that an unnamed witness thought that British submarine Turbulent may have been involved in the ship's sinking.

[19] On 31 July 2008, the judges Richard Foltzer and Muriel Corre, who had been charged with the inquiry into the sinking of Bugaled Breizh, after having received expert testimony, issued a statement that a "highly probable cause" that the vessel sank was as a result of an accident with a nuclear attack submarine.