In 1.13's snapshots, since the Underwater changes have been made with the lighting and such, the Overlay texture, found in the "textures/misc" folder, has been unused by the game.
This has given the underwater an unusually clear(moreso than it's been changed to be) look, due to the lack of the bluish color overlay.
Since there has been no mention of this change, and with the texture still being there, I must assume it's just not working properly.
I not only request this be fixed, but also request to know what the reason of this change is and why it hasn't been mentioned before.
Duplicate of MC-128337