When you visit the Sunken Cities exhibition at the British Museum, you feel as if you are diving beneath the waters of the Nile River. You pass through a corridor illuminated by blue light and into galleries painted in a navy blue. There are dappled lighting effects to imitate water – it’s a wonder they don’t hand out snorkels to complete the illusion. The idea works, however, and you feel just like the archaeologists whose work has formed the basis for this display. It is as if you are discovering a world that has been hidden for more than a thousand years.