I had a similar moment. I was deep around one of the structures the story leads you to, in my seamoth. I had upgraded the depth on it and was hovering just above anything that would crush it, but still able to wander around in the cave to the location. It’s spooky as hell and I’m shining my lights on the structure so I can dart in and out based on my oxygen level.
Then I started hearing these strange creature noises followed by a tick tick tick … tick. What the hell could that be? Then this deep DUUUUUUUUM and screeches. Spoiler: sounds I look out and see my seamoth getting it’s ass kicked by a bulbous headed squid. I freak out and watch it attack some more, realizing I am inside a structure, that’s my only air refill point, and I’m several hundred meters down in a cave. Fuck. Sure enough, a few seconds later I hear my seamoth pop. Gone to the depths. I made it about half way back on the seaglide before my air ran out.
It wasn’t until much later I heard the voice of Sgt. Al Powell from Die Hard in my head, “They’re shootin’ at the lights!” The thing didn’t like the lights on my seamoth being on. :(
RIP Seamoth #1