It's a fantasy role-playing game.

DM: You are Fjord, a half-orc warlock . You are the member of the famous group of adventurers. Previously, you anxiously jumped, worried about what Avantika will do if he does not catch up to her. The well continues down almost 80 feet; strangely, it is salt water.
DM: You begin to close the gap slowly, but she's eagerly swimming down with almost a fervor. As you get deeper into this column, this basin below, the walls begin to grow thick with algae and grime like a thick-- It could be a plant matter that's just accrued over the walls, or it could be waste matter from the hydra in its home that has slowly congealed to cover the walls. The stone begins to give way to this dark, slick material. Once you hit about the 70, 80 foot point, the tunnel begins to open like a giant bulb or internal, spherical chamber. Role another athletics check.
Player: 14.
DM: She's still keeping her distance from you. Heading deeper in, the saltiness of the water, the brininess, the flavor in your mouth gets more intense. What was once a semblance of sea water is definitively sea water, but also very strongly briny sea water. Make another athletics check.
Player: The bulb-- we've entered that chamber, right?
DM: Correct.
Player: What's our visibility like? 40, 60?
DM: For you, because you have dark vision, you can see within 30 feet of you, essentially. As far as you look the chamber is--
Player: There's not a lot of natural light, right?
DM: No. Not at all. It's pitch black down here. That being the case, you don't see the bottom of the chamber, you just see it open--
Player: And just her.
DM: And just her, but she's gaining.
Player: James Cameron going down to find the Titanic.
DM: Just delving straight down into the darkness. Make another athletics check.
Player: 20.
DM: 20, okay. She did not role that well that time. She's beginning to tire, it seems, or at least you're starting to pick up speed. As you continue to follow, you get probably 40 or so feet from her, but she's still ahead of you. Role again.
Player: Natural 20.
DM: Natural 20, nice! She rolled okay. You see, now, the bottom begin to approach. In the peripheral of your dark vision, the floor greets to meet you and you pick up enough speed to where you both impact the bottom of this chamber at the same time. You both hit. She looks up at you, and your eyes meet. A few bubbles escape from her mouth and you see her big, wide, toothy grin and she begins scraping grime off the floor.
Player: I do the same.
DM: All right. Make an investigation check.
Player: I don't know what I'm looking for. 23.
DM: 23!
Player: Plus five.
DM: As the two of you are currently scraping bits of grime and algae off the ground, there are bits of plants that are growing up like lightless kelp that seems to have made some sort of a living down here in this subterranean, water-filled chamber. As you're pushing through and scraping around, your hand scoops this large bit of grime from in front of you and you can see a stone relief at the very base of the bottom, a concave, spherical shape about the size of a fist.
