The Utter Inn may lack the jaw-dropping luxury of other resorts on this list, but at least this Swedish undersea hotel actually exists.
Half of the Inn, which Mikael Genberg created as an art project in 2000, is visible as a red shed-like structure floating atop Lake Mälaren in Vasteras.
Guests scuttle down a ladder to reach the simple underwater living quarters: two small beds below a picture window that offers a view of fish and other lake life. The Utter Inn is listed on the swank rental site PrivateIslandsOnline.com, starting at $1,750 for seven nights.
The median sales price of a vacation home in 2012 was $150,000 -- up 24% from the prior year --and this summer could be another sizzler.