It was August, so it seemed a perfectly sensible idea. I'm in Norway, land of the fjords—let's go for a splash in one! Bergen has a lovely little lido that offers you just that opportunity. Sure, you can swim in its heated outdoor pool, but the real attraction is the small roped-off area of (lifeguard patrolled) fjord. Having warmed up—not literally—in the lido, I dipped my toe in the sea and, before I could register how cold it truly was, launched myself in. It was cold. Colder than an ice bath. Colder than locking yourself in a beer cellar (it's not that far, remember, from the Arctic). And, once my horrified body had recovered from the shock, it became one of the most enlivening experiences of my life. Just don't stay in there too long.