For disclosure, I do suffer from this phobia. And it hasn't stopped me from enjoying the game a ton. However, the pond section of the game is really unsettling for me. I have to deal with fear of deep bodies of water a lot in video games, and usually I either just avoid the game completely or find some weird workaround to make it less unsettling. I normally wouldn't even bother suggesting something like this, but with the arachnophobia mode in the game, I feel more comfortable that Obsidian would at least consider it. I don't think it is statistically as common as arachnophobia, but I think the ability to make the deep water section less uneasy would not require much (I say this with no development background, so I could be very wrong).
For instance, I think thalassophobia mode could eliminate the atmospheric depth lighting from being underwater (allowing you to see to the bottom of the pond). Also, it could remove or reduce the watery vision effects and increase the gamma.
In Fallout: New Vegas, if you took Cateye (a consumable that lets you see in low-light areas), it completely removed the creepy feeling of being underwater for me. So something similar to that effect could help.
