Isola Polvese in Lake Trasimeno is a small gem worth visiting. You can take the boat in San Feliciano, the boat trip takes only about 10 minutes and during these ten minutes you will really start feeling you are on holiday (suppose you did not yet feel that way before!). You see San Feliciano slowly getting smaller, sea gulls swirl around the boat and many other water birds pass by.
Isola Polvese has a bar and restaurant. You can walk over the small island, it does not take long. There is a castle and you find olive groves, all well maintained and clean. On the other side of the island there is a big beach where you can do some sun bathing before going back with the boat. The island is a nature reserve.