I think it would benefit from a ground up overall. Because of the increased movement and lack of AoE fields the current depth of engagement feels shallow and hit-for-hit-ish. (almost like a more traditional MMOs ground combat).
I really think that before a major under-water themed content patch comes out, the Development team needs to play a ton of space or naval themed games to find which elements of this can be made FUN, and incorporate them into the weapon sets provided.
I’m sorry I don’t have any good suggestions in this post, I’ve tried figuring out how to make it more fun and came up blank — making it entirely understandable how things wound up in their current state. But under water combat feels about as well polished as downed states.