How about kite surfing?
My first trip to Vietnam was intended to be about food and culture, but I ended up getting a little sidetracked for a day and enjoying beach life in a place called Mui Ne.
Famous for its sand dunes, which give it a totally unexpected look and feel for tropical Southeast Asia, there is a bit of wind action off the coast - this helps maintain the dry air and shifting sands required for dunes; but it also helps people lift off on the waters.