You hoist your towel above your table, drop into the water and sail away. You turned the towel into an actual sail and you're balancing on top of the table, which is now a boat.
As you sail off into the ocean you hear a familiar voice shout out, "Ahoy!" Han (はん) Solo calls. He's also got a towel sail, but it's on the Millennium Falcon, which is half-submerged in the water.