Flight 29 Down: The Hotel Tango (movie, 2007)

Flight 29 Down series finale. The castaways split into two groups. One stays on the beach, and one travels to find life on the island. Just when they think the place is deserted, they find an old concrete hotel used in WWII, along with other old buildings rotting away. They find the pilot, and the two other survivors in the hotel. The pilot has a bad sickness that makes him go crazy.