The lanyard alone will fail.

It will.

Most waterproof phone pouches come with a cheap plastic clip that pops open when you dive, splash, or just move wrong. The lanyard is not the problem — the weak clasp is.

The fix is either to replace the clip with a small locking carabiner (the kind with a screw-down sleeve) or to use a pouch that has a proper twist-lock buckle. A secondary waist strap helps if you’re doing anything more than floating on your back. Some pouches even come with a floating lanyard that adds buoyancy so you don’t lose it to the bottom if it does come off.

Don’t trust the default hardware. Swap it out before you get in the water.

Save your phone by spending an extra five bucks.