I’m walking around Castle Island in South Boston, and its accompanying body of water, Pleasure Bay, and notice some huge kites in the sky. Not so unusual. Then on the beach some chaps in wetsuits—again, not so unusual. Then one of them grabs the giant kite and a surfboard, and proceeds to launch himself into the water, on the surfboard, harnessing the power of the kite like a sail and floating up. It’s called kitesurfing, and I’d never seen anything like it.