I have not found anything other than a few chests underwater so I have not explored much underwater. Anyone find anything worth talking about while breathing underwater? I have not gone to the Dwemer ruins near the Telvani tower in Solstheim yet.

There's some Nordic ruins in the lake, and some sunken ships here and there.

I never used any water breathing in the DB ruin, it's just not needed. Honestly I generally loot most sunken ships and such and just never need water breathing. Really makes the Argonian racial ability completely worthless.

I suppose the fact that you can not attack underwater anymore makes any underwater adventure kind of pointless.