Last summer we were allowed to walk around on Penikese. It was between being a school
for troubled teens and I think now an adult rehab center (?). There were a few workers and staff people on the island fixing the main building up for its new role, and they said it was okay to walk around.
Fascinating place -- former leper colony, with the ruins of the old "leper laundry
building," some huge brick cisterns, and a leper graveyard. Beyond that, it's just a beautiful little island, lightly trodden upon by modern times.