Swimmers have been testing the waters of the UK's first geothermally heated lido, which is set to open to the public on September 1. The first events are open to the 1400 local people who helped finance the £1.4m project.

Salt water is pumped underground to a depth of 410 metres where it is naturally raised by the earth's temperature, with additional pumps then bringing the the water temperature up to around 32 °C.

First reports are extremely positive and swim sessions are proving popular, with many being booked out online as people come to Penzance to feel the heat. Evening sessions will be opened later in the year.

It's true that the Romans did it first, 2,000 years ago in Bath, but you're not allowed to swim in that one!