Anti-Fog Insert or Coating

A fogged mask ends a snorkel session faster than cold water does.

Polarized Against Water Glare

Reflected light off a lake surface is harsher than open sky above it.

Strap or Leash Retention

A wave takes unsecured eyewear, and it does not come back to you.

Rinses Clean of Salt

Dried salt hazes lenses and seizes hinges after a day in the ocean.

Visible in Low Light

Dusk paddles depend on other boats picking you out on the water.