Thermal baths in the United Kingdom

Porchester Spa in London is men only on Monday, Wednesday and Saturday, women only on Tuesday, Thursday and Friday, and mixed on Sunday; bring your own towel and swimwear. Ironmonger Row Baths near Old Street is mixed apart from a women-only session on Tuesday mornings. Harrogate is mostly mixed, with a ladies-only session on Tuesday evening and a gentlemen-only one on Wednesday evening, and swimwear at every session.

Porchester Spa is 18 and over, and Harrogate, Ironmonger Row, Newcastle City Baths and Portobello 16 and over. At Thermae Bath Spa the New Royal Bath is from 16, while the Cross Bath takes 12 to 15 year olds with one adult each. Thermae asks for proof of age.

No, phones are locked in a pouch for the visit. Spa sessions last two hours, swimwear is worn in all public areas, and you bring your own footwear. Direct trains from London Paddington reach Bath Spa in about 80 minutes.

No, it's closed for repairs. The baths are inside a Category A listed Victorian swim center on Portobello Promenade, built in 1898.

Yes, at nearly all of them. Ardagh, Suvi and Wild Sauna in Bristol, Derby Wild Sauna, Puffin in Edinburgh, WARMTH in Sheffield, Skuna and Rooftop Saunas in London, Kiln in Cornwall and Braan Sauna in Dunkeld require swimwear, and HotBox and Niche Coastal in Northern Ireland don't allow nudity. Community Sauna Baths in London, Bristol Community Sauna, Glasgow Community Sauna, Soul Water around Edinburgh and Beach Box in Brighton ask you to cover the lower half, with tops optional. Sweheat at Royal Victoria Dock runs a German-style sauna event with full nudity.

In England, Wales, Scotland and Northern Ireland. In England there are beach saunas on Longsands in Tynemouth, at the Banjo groyne in Brighton, on Great Western Beach in Newquay and on Kiln's three Cornish beaches at Flushing, Falmouth and St Ives, plus Suvi beside Clevedon Marine Lake on the Severn Estuary and Revival at Leigh Marina on the Thames Estuary. Wales has one on the promenade at Aberystwyth, Edinburgh has them at Portobello and Granton, and Northern Ireland at Groomsport Harbour, Ballycastle, Portstewart Strand and Benone Strand. Hide Sauna stands on the shore of Windermere, and Wyld Sauna in Liverpool has a roped swim area in Princes Dock.

At some, with limits. Ardagh and Bristol Community Sauna, Wyld in Liverpool, Rooftop Saunas, Mile End, Sauna Social Club and Urban Heat in London are 18 and over; Puffin, WARMTH and Sweheat take no one under 16, and Braan Sauna in Dunkeld no one under 17. Community Sauna Baths in London welcomes children from 7 with an adult, Suvi from 8, and Kiln in Cornwall takes 6 to 16 year olds in family and private sessions. Saunadelic in Hove runs family weekend sessions for children aged 1 to 15, and Olla Hiki in Newquay welcomes children over 5 with an adult.

Yes, at Buxton Crescent Spa, where non-guests can buy four-hour spa sessions. Its thermal pool takes Buxton's mineral water, heated and left chemically untreated. The thermal spa is for 16 and over, and Buxton railway station is about a 5-minute walk away.

At Soak Seaweed Baths on the South Promenade in Newcastle, County Down, which the operator calls the only seaweed bathhouse in the UK. Each private, lockable room has a bath of hot seawater with seaweed hand-picked on the South Down coast, plus a steam pod, so swimwear is up to you.