It is not likely, but it depends on what material the walls are made out of. Mud, probably not, but tile yes.
There isn't a specific term for such a thing, beyond "pool"!
Turn the pool upside-down and knock on the bottom.
Aggressive water chemistry and age.
You drain the water then plaster the walls from inside
to calculate the content of the pool go to this link
Air bubbles in the water....
20,500 gallons
well there is a under water cave or they is a little tunlle of some sort and ya
No. An underground pool needs strong walls to hold the soil out (when it's empty) and the water in. Usually they are cast concrete.
cave men on walls of cave in a cave
cave men on walls of cave in a cave
NO however you should keep in mind that the ground water outside of the pool is not going to put pressure on it as this is capable of even lifting a concrete pool out of the ground.