Hotel Schloss Seefels

The pool here is enclosed on the sides but open at the bottom, so you're essentially floating in a heated frame set directly in the turquoise water of Lake Wörthersee, year-round. This boutique lakeside hotel is the Gatsby-esque kind: tiered lawns, open terraces, a tropical spa with gold mosaic tiles, and guest rooms with balconies over the water. The Schlossbar's Baroque chandelier and marble bar make it a perfectly reasonable place to order a whiskey at midnight.