Inhabitat is my go-to place for gorgeous, innovative, ecologically sound design, at least when I am planning for a future multi-millionaire version of myself, and I was delighted this week to discover, via them, the submersible swimming pool. When you want to swim, it’s a pool; when you need an extra room, you disappear the pool and get an elegant stone floor in its place. What I especially like about it is that it looks quite a lot like something out of Harry Potter (you will have to visit the website to see the full effect). This is top of the list for features in my fantasy home, alongside the cassette lamp and the toilet that you wash your hands in.