Flagstaff, Maine
Credit: Daniel J. Grenier / Getty Images

The conditions need to be just right if you want to see any part of Flagstaff, a now-underwater town in Maine that was submerged in 1950 to make way for a hydroelectric dam. And even then we're not promising you'll actually see anything. But because not all of the buildings were removed at the time of its flooding, you can still get a peek at a few chimneys and rooftops.

Getting there: It's best to let an expert like Jeff Hinman, who runs a two-and-a-half-hour pontoon boat tour, guide you.