One of the fastest growing design trends is the ‘outdoor room’ – and what could represent a better focal point for this than a super-cool hot tub? Whether you use it for private relaxation or partying, it’s a brilliant way to create water-based fun – cheaper than a swimming pool and requiring less space. And unlike a normal outdoor pool – which, let’s face it, has only limited appeal in the great British climate – you can use it all year round.