A very large, enclosed cavern with a creek running through it.
The player sinks in the creek and may fall to the underneath area where they must take an elevator to return to the beginning.
Platforming
Fairly easy.
Player is forced to cross the winding creek at several different points
Platforms are half submerged and sloped enough that the player can walk up them.
Platforms get further apart near the end
Dialogue
Guy on Radio
After falling for the first time: "You still there? Remember to sprint"