An art deco outdoor swimming pool at Tarlair in Aberdeenshire has been given the top status by Historic Scotland.
The Tarlair art deco complex was built in the 1930s
The tidal pool, built in the 1930s, has been granted category A-listed status because of its architectural and historic importance.
It is one of Scotland's three surviving outdoor seaside swimming pools.
The A-listing gives the "simple yet stylish" Tarlair pool, near Macduff, legal protection to ensure it is looked after properly.
Dr Debbie Mays, Historic Scotland inspector of historic buildings, said: "Tarlair is especially interesting because of its simple yet stylish art deco design which has remained pretty well intact through the decades.
"The complex is also important because it is an early one, and because it included a boating pool as well as the ones for swimming and paddling."
The large swimming pool plus paddling pool, boating pool and tea pavilion were the very latest in seaside leisure when they were built in 1930-31.
Architect John C Miller, who was the burgh surveyor for Macduff, designed the swimming pool's outer wall to be fractionally below high tide level.
Being A-listed provides legal protection for Tarlair
Waves rolled in over the edge, giving swimmers the pleasures of the sea in a controlled environment. It also meant the pool was refilled with clean water twice a day.
Dr Mays added: "Outdoor pools were highly fashionable meeting places in the 1930s, especially at the seaside.
"They were built in quite large numbers and have an important place in our social history but few now survive, so it's great that we still have such a good example as the one at Tarlair.
"The whole idea was to offer families lots of different ways to have fun at an elegant pool complex with a superb natural setting in a spectacular rocky bay."
Being A-listed provides legal protection aimed at ensuring the complex is looked after and that any changes are carefully managed to maintain its authenticity.