Another of those great images of sea phenomena that I like, cross (or grid) waves, which occur when two sets of waves travelling from different directions cross at an angle of 45° or more. This creates very steep short-crested waves that can be dangerous for shipping. From the European Space Agency.
Put some Channel Swimmers out there, you could have a game of Sea-Chess and get some good training in.
EDIT March 21st 2013: This post is getting a hammering from people that don’t believe this is real. Please check the comments for my update & explanation (that it is genuine and how it can be caused), and also a way for you to check the photo for yourself, if you believe the European Space Agency (and I) are lying to you.
Update Sept. 2014
Here’s video of a similar phenomenon on a beach. The result is the same but the cause here is probably angled sandbanks causing wave refraction where waves wrap around an object because one end of the wave gets slowed down by shallower water. Wave refraction is what causes such famous surfing breaks as Malibu in California or Jeffrey’s Bay in South Africa.