Back when I was a kid, there was a pay to enter beach at a nearby lake. It had a fence on both ends running out into the water. My clever brother didn't want to pay a quarter to get in, so he swam around the fence and into the part of the lake where the beach was. The owners caught him and said he had to pay. He said you own the beach, not the lake. So, as long as he didn't use their pier or raft he was allowed.