Iroise Sea

Iroise or the Iroise Sea (French: mer d'Iroise, pronounced: [i.ʁwɑz]) is the part of the Atlantic Ocean which stretches from the Ile de Sein to Ushant off the coast of Brittany in north-western France. It is contained within the Celtic Sea, bordering the remainder of the Celtic Sea to the north and west, and the Bay of Biscay to the south. It is one of the most dangerous seas in Europe for sea-going vessels. In winter, there are often violent storms with huge waves. It is also one of the richest areas for marine life and was designated as one of UNESCO's biosphere reserves in 1988 and as France's first marine park in October 2007.

The name is first recorded in the Neptune francois of 1693 as Le Passage de l'Yroise (passage = "channel"); as Passage de l'Iroise in the 18th century; as Iroise in the 19th century; and as mer d'Iroise (mer = "sea") in the 1970s, by the seabed exploration industry. The name appears to have been fixed not by local seafarers but rather by staff at the naval base at Brest. The 18th-century maps identify "Passage de l'Iroise" as the channel leading north-west from Pointe Saint-Mathieu and keeping south of Ushant and the Ponant Islands. From the 19th century, the term Iroise encompassed all the sea along the west coast of Brittany between Ouessant and Sein. While this remains the limit used by mariners, some twentieth-century sources have used mer d'Iroise to denote the entire Celtic Sea as far as Ireland and England.

The meaning of Iroise is obscure; theories include:

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