Walchensee & Sassau Island (Germany)

A view of the Walchensee from Herzogstand. Locals call it the "Bayrische Karibik" or "Bavarian Caribbean" because its calcium-carbonate-rich waters glow a bright Tiffany turquoise with up to 40 meters of visibility. The tiny island of Sassau sits within the lake and is a protected nature reserve where landing or approaching within 50 meters is illegal.