Lanes go in 45-minute sessions you can book up to a week ahead. If a lane is free you can just walk in: the board by the gate shows which ones.

All year round: 25 degrees in the long pool and 30 in the shallow one. On cold mornings the steam rising off the water is half the fun.

A swim cap, a coin for the lockers and a towel, or borrow one at the desk. Flip-flops help on the deck when the tiles are cold.

From eight years old, after a short swim test at the desk. Younger children swim with an adult, one grown-up for every two children.

We clear the water at the first rumble of thunder and wait half an hour after the last one. Your session goes straight back into your account.