Development has been fairly slow coming to these areas and the locals
have had use of the islands for generations. Someone buys up the
property, uses it for a few weeks each summer and then guards it like a
national treasure the rest of the year. No one allowed on or near the
islands. Some even try to evict boaters anchoring in the coves...
although they only own property above the high water mark.

Yeah, imagine why they'd be upset to come back during those few weeks only
to find those freeloaders had peed and **** all over the place, lit fires,
left trash and generally made a mess of it. Of course, they'd be rightfully
rather mad about it and seek ways to keep the rabble out.