Its central building is a water plant that opened in 1884 and operated for a century until 1984, when it became the property of Arcachon town council in return for a symbolic fee of one franc.
Though it was ravaged by fire in 1990 and spent several years in a derelict state, it rose up from the ashes last year to be reborn as a luxurious, inventive and atmospheric hotel.
Its former life as a water facility is best viewed from the side of the pool - which was in fact sliced out of the original underground reservoir. Many of its features - including the funnel-shaped Victorian water pipes and smoothly curving ceilings - are in evidence. As you languish here in fluid serenity, these are reminders of its hardworking liquid past.
(Thanks to super shooter Vaughan for the photos, which he took while I was busy snooping around the grounds...)