Open water kills more swimmers than pools, by a wide margin. It's not because the swimmers are bad — they're often strong pool athletes who get caught out by something a pool doesn't have: cold, current, distance to exit, and the simple fact that no one is watching. The fix isn't to swim less; it's to build a small set of habits that you don't skip.
Tell someone your plan. Where you're entering, your rough route, when you expect to be out, and what to do if you're not. A text message before you go in is a 30-second insurance policy. If you swim alone, share live location during the swim — most phones now do this trivially.
Wear a tow float. Bright orange or yellow, attached to your waist, drags behind you. Two jobs: makes you visible to boats, and gives you something to rest on if you cramp or panic. They're ten pounds. There is no good reason not to have one.
Pack your "warm pile" before you swim. Dry layers, hat, shoes, hot drink in a thermos, blanket, ready to grab in 60 seconds. The afterdrop (your core temperature continuing to fall after you exit) is when bad decisions happen — if you have to fumble in a wet bag for socks, you're already cold-and-stupid by the time you find them.
Know your exits. Before you start, identify at least two places you can get out — not just where you entered. Wind, current, or a cramp can push you off course. "I'll just swim back" is not a plan; it's a hope.
Honour the cold-stop rule. If you can't close your hand into a fist, get out. If your stroke goes janky, get out. If you stop feeling cold (paradoxical warmth from late-stage hypothermia), get out *immediately*. You're not being soft — you're recognising a signal your body sends exactly once.