Enjoyed the demo very much. Loved the humor, the idea of a 'broken AI' in charge, and a possibly sinister company. Reminded me of Aperture Science, good times.
The swimming speed could probably be upped a bit, since it takes too long to swim to a destination and nothing is happening, makes the player feel bored. (on the other hand, looking behind on the last level was not a good idea)
Probably more interactions could be implemented (I assume there are some already planned), as it can get repetitive fast if it was only welding/cutting and unclogging.
Being mainly underwater focused, I could see also having levels or parts of them where you are not in the water, but rather inside some old abandoned complexes where you explore those.
Overall, its really good.