A jewel on the Baltic Sea, the Finnish capital of Helsinki is a city of water, water everywhere. Arguably the best way to see everything is by boat, so test out your sea legs on a ferry. If you have H2O-loving kids, visit Serena Water Amusement Park, with whirlpools, water slides, and a wave pool open year round. Adults can enjoy the traditional sauna culture, which is huge here. Visit the wood-burning Kotiharjun Sauna, dating back to 1928, for a chance to sweat it all out. And make room in your schedule for plenty of coffee breaks: Finland consumes more coffee per capita than any other country in the world, and they mean business when it comes to café culture.