"He began work on the piece in 1903, but in 1905, he traveled to Eastbourne, a seaside town on the southern coast of England, to finish the score. "

http://facstaff.uww.edu/allsenjm/MSO/NOTES/0102/Feb2...

"'La Mer', a complex sound picture of the sea. This piece was completed in the Grand Hotel, Eastbourne, on the south coast of England"

http://www.artsworld.com/music-dance/biographies/d-f...