The issue is:
a) You can't manage resources until you reach a point where the game lets you manage them. And the Obelisk drains your water at like 3x normal speeds, so I'm not sure how you expect a player to manage their water effectively with a drain like that.
b) Except you can't do an action right, the first time, without at least dying once. That is a frustrating death. You aren't warned at any time that approaching Santorini could be dangerous. The logs from people fleeing the place, don't explain why they were... much like how the people from Talos didn't explain what was at Talos that was so bad that they abandoned you, left for Laurion, and then people disappeared from there.
c) Actions that kill you for a set piece, is the same basic idea as "haha you did a stupid and died now." You could have had it where Santorini explodes before you approach it and then you arrive at a blast crater, and then realize you need to get here faster next time, instead of outright killing the player. Oversight perhaps?
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Now I'm not suggesting you add in "kill events" for the purpose of trolling the player. I'm suggesting putting them in there for side stories, easter eggs, or to make future content make more sense.
Like we do have a button that lets us suicide after all, and end a loop prematurely. So, the concept of death events that could provide other content, is something that could add immersion.
As for the pressure regulator, I forgot where I found that thing. Thanks for reminding me that is where you get it.
As for the obelisk, I've never drilled through that last layer, so I don't know what benefit it provides. Frankly, its too much work to find out. Took me 5 loops just to get down to that layer, as I kept running out of power at Laurion.