Lbracer said..
What are the little canister things that he attaches to himself?
They are compressed air to inflate the buoyancy vest most of the big wave windsurfers / surfers wear. Several metres of foaming surging white water is mostly air (surprisingly) so that it's almost impossible to swim, let alone float, through it. The canister inflates the vest enough to give the extra buoyancy to get back up from a bad hold-down. Some versions have a mouth piece so that the sailer / surfer can grab an extra bit of air if things get really bad... There is an excellent explanation of all this as well as lots of other stuff in a book called "The Wave..." by Susan Casey. A fantastic informative, scary read!!
