Just offshore from Kas is the geopolitical oddity of the island of Meis. Despite only being a 20-minute ferry hop away from shore, Meis actually belongs to Greece (and is known as Kastellorizo in Greek). A day trip here from town means you're actually crossing an international border.
Meis has plenty to keep you occupied for the day. The most popular things to do include boat trips to the island's coastal caves and some great hill hiking to abandoned church ruins