They were extremely popular in the 1930s, but the Stonehaven Open-Air Swimming Pool, an aging art deco gem, is one of only a few remaining outdoor heated pools in Scotland. Salty water from the North Sea is pumped in and warmed up to a toasty 28°C (82°F). Run by a local trust, this place is perfect for families. Wednesday's midnight swims (£6.50) let you float under the stars.
Queen Elizabeth Park, Off A90, Stonehaven, Aberdeenshire, AB39 2RD, Scotland