Aquatic Vision

Your eyes are optimized for seeing underwater, so in air, they dry out easily and refract light differently, causing everything to be blurry, especially far away. This gives you disadvantage on all ranged actions and attacks that require aiming but no vision penalties when underwater. You also need to blink more often, which doesn’t affect game mechanics, but those who don’t know you will notice when you interact with them. This disability does not have an IE and is usually permanent. If the player and GM choose this as a temporary condition, it should not use immersion in water as a trigger (which would negate the disability) but could be triggered by moon phases, tidal fluctuations, or other sea-related factors.

Real-world Examples

Significant nearsightedness, the Moken people of South-East Asia. This trait should not be confused with fish eye disease, which causes clouding of the cornea and no advantages to seeing underwater.

Assistive Options

Wearing goggles filled with saline water can correct for this condition, but they slip off easily and require 2 actions to replace the water in them and refit them to the eyes. Anytime you take damage or make a roll based on Strength or Dexterity, you must succeed on a DC 10 Dexterity saving throw to keep the goggles on.