Confession time – Once upon a time, I gave in and allowed my (teenage) swimmers to try this on the insulating swimming pool cover, after they had been begging for weeks. It was really, really fun, arranging relays and stuff on ‘dryland’ across the pool, right up until one of them went through the (old and battered) cover. He went right through and disappeared, it was still pretty funny and I guess not that dangerous … but the cover was wrecked.

So, the next morning, I had to call the janitor and explain. Not at all as fun as running on that (expensive) piece of rubber. You’ve been warned.