Finns really know how to relax. Finland's official travel website boasts that there is roughly one sauna for every three residents—or about two million total for the country of 5.3 million people. And at least one of those saunas floats.
A group of friends got together to create the Saunalautta, a houseboat with bunk space for five and sauna space for up to 15 (depending on how cozy a steaming experience you're comfortable with). Ascend the ladder from the main deck and spend the day jumping from the roof terrace, complete with a BBQ and 19-foot diving tower.
Nice touches: a sound system wired throughout the vessel, a fridge, a heated shower, and a classy dark green wood exterior. Plus, it's a real, moving boat, which means you can take the party wherever you like.
Rent it for about $410 per day.