One for the update that just hit - make bases safe zones for radiation - just watched the start of the explosion, then I got 'Radiation Detected' inside my base
A nice thing would be for the bubbles to stop when you equip the re-breather, as they way they work is by recycling the air you breath - they are nice and quiet, with no bubbles.
Nitrogen turns in to a narcotic at approx 18m this could turn in to an interesting game mechanic - you need to source helium, or increase the oxygen to limit the effect (More things you need to source, to go deeper)
Could there be an option to see the swim visual or not, or to have the swim visual at the start (when you have no fins) then remove it when you get fins. It also works well on the surface - but I am finding it incredibly annoying underwater.
Storage is the biggest issue, a small storage area in the pod would be nice at the start, or one that floats that can be built by the constructor - so you can store the material to build the cyclops
I have just signed up for Earliest Access - I look forward to working towards a decent underwater game. As a SCUBA instructor, Technical Diver and Rebreather user I hope I will be able to be of some small help to achieve this.