How do I exit the cistern?

[Cranky Old Man]

The path should not be blocked at all, you easily can enter the door as far as you reach it. I just sprinted the waterpool until the end, it is not a big deal to avoid Kaernk.

Sometimes the red slime and the Kaernk doesn't appear. I believe it depends on whether you save this task for last or not, but other people say it depends on how much sanity you have.