Yeah I’ll probably wait until full release of Sub Zero as well, I’m just really curious already =)
About the Jelly Caves - I actually never found an entrance to it. My game is a bit buggy at times with loading the world, so when I was out looking for the signal of the Degasi-base down there, I came across a square of the ocean floor that was just… gone. Or not loaded. I went to that bottom and my Seamoth just kept going down, for a few meters I was just completely disoriented with travelling in “nothing” - then suddenly I was in the Jelly Caves.
Really easy way in, if a bit unsettling =)
I actually found the blueprints for a lot of different buildings like the moonpool, the seamoth and different rooms and upgrades, long before I found the blueprint for the Mobile Vehicle Bay. So it took some time before I got the Seamoth built.
I put that out for quite some time, but you definitely MUST have the radiation suit, the repair tool, the propulsion cannon and a laser cutter. It took me some time to find the blueprints for the las two (I actually think I found the blueprint for the Propulsion cannon ON Aurora, in the only accessible point without it, so I had to take two runs there).