Posted: 21/08/2012 at 14:32
We stayed near there on the way back from Ironman Switzerland in 2009. Loads of good campsites, a lot of them next to the beach. The beaches are sandy but rather shallow for swimming especially when the tide is out. Dunkirk is a bit industrial with a large oil refinery next to the port.
This is definitely a possibility for next year. Note the 15.5 hour cut-off though.