Local boys and girls like to jump into the sea from the pier.  Please mind It is steep and deep under the pier and you had better stay away from Sesoko Ohashi Bridge because of the strong current.  You can try that if you want, but do it at your own risk in the sea.  If you want to enjoy the beach, go to the opposite direction of the pier.  There is a beach house where you can get refreshments, rent marine equipment, and take a shower.