Carden Park hotel in Cheshire has started work on a £10m spa, set to open next summer.
The spa will be the centrepiece of refurbishment works at the 198-bedroom hotel, in which £20m has been invested over the past three years.
It is being built as a separate facility and will welcome both day visitors and overnight guests.
Among the facilities on offer will be an outdoor spa garden which will include a sensory hydrotherapy pool, hot tubs, fire pits, an outdoor sauna and a "secret garden" relaxation space.
Inside the spa, there will be a range of different thermal experiences, a large pool, ice fountain, snow shower, foot baths and heated loungers.
There will also be 14 treatment rooms and a beauty lounge offering manicure, pedicure, lash and brow services.
Carden Park general manager Hamish Ferguson said: "Carden Park is constantly innovating and evolving to meet market demands but this is a momentous leap forward for the business as we invest in what will be one of the most luxurious spa developments in the UK.
"Not only will it offer Cheshire residents a place to relax and socialise but it will also prove an important added attraction to the luxury leisure break market. We have an incredible team of people involved and I'm looking forward to what will be a very special spa journey for us all."
Carden Park is owned by Steve Morgan, founder and chairman of housebuilder Redrow.