Swimming: not one of them.
You’ll have to wait till the iPhone 11 for that feature.
In the meantime, how about a life jacket... that also plays music...
Presenting the EcoXPro, a floating, waterproof speaker that allows you to toss your phone into the middle of the Atlantic Ocean (or the middle of a pool), available now.
This thing is basically a buoy. An orange, floating, Huey Lewis–playing buoy. Only instead of marking no-wake zones (or whatever it is buoys do), it’s a virtually indestructible speaker/case/flotation device in the event of a water landing.
To get one, go online. Order it. Then wait for the mailman. Then wait for a pool day. Pop open the case and hook your phone to the headset jack inside. You: go on a raft. The speaker: goes in the water. The volume knob: goes full blast. So you can hear it. At the bottom of the deep end.
Also in this case: enough spare room to hold your other non-seaworthy essentials. Like keys. Or a deck of cards. Or a wallet. Or a really small turkey sandwich.
No, the 30-minute rule doesn’t apply.