The pool water is heated by solar panels on the roof
The Victorian Clifton Lido in Bristol has reopened after two decades and a £2m revamp.
The lido, believed to be one of the oldest Grade II-listed swimming pool in the UK, closed in 1990.
People living nearby campaigned for the facility to be protected and restored to its former glory.
The facility now has a sauna, a hot tub and poolside bar but the water in the main pool is expected to take two weeks to reach working temperature.
The lido was designed by Bristol architect Richard Shackleton-Pope in 1850.