Seamoth could have an artificial horizon

Flappybat

The Seamoth is extremely responsive to control input and in the dark with limited points of reference it can be difficult to tell how it is orientated. It can even go upside down temporarily. There's two unused display panels which could be a good place for one.

Kouji_San

Exactly, it is kinda an underwater plane the way it flies through the water

Artorius

Since the Seamoth doesn't bank or roll, only tilt, I think an attitude tape overlay in the HUD would work. Showing degrees of climb or dive angle.