With the natural water vision addition, the visibility is too high in the water with various different environments. For instance, swimming in a cave will let the player see more than if they were standing out of it, and swimming in an ocean at night will let the player see much more than if they were on land or on the water's surface.

Video: https://www.dropbox.com/s/ba914rnn86xi4k2/Lighting%20Hacks.mp4?dl=0

A fix for this could be that the water vision is applied to the water based on the highest light level touching it (water vision increases while going closer to a light block), or that the light level (active sky and artificial) decreases slower when travelling through water blocks (like Subnautica). The second option includes that the new water vision is removed from the game though; giving night vision, water breathing, respiration, and submersible light blocks a purpose (The water will actually have light instead of the player having night vision).