70°F is the cutoff for safe swimming.

Below that, your body loses heat faster than it can produce it, and the risk of hypothermia and cold shock goes up fast. Most people start shivering around 70°F (21°C). Shivering is the first sign your body is losing the battle.

That said, a quick dunk in 68°F water isn’t going to kill you — but a long swim can. Cold water saps strength, numbs limbs, and makes it hard to breathe. If you’re not used to it, anything below 70°F is asking for trouble. Kids and older adults are even more sensitive.

If the pool feels uncomfortable getting in, that’s your body telling you it’s too cold. Listen to it. No swim is worth a trip to the ER.

A five-minute dip is one thing. A swim session in the 60s is another.