A geothermal pool is called a reservoir.
aquifer
Aquifer
An underground geothermal pool is a body of hot water that is heated by the Earth's natural geothermal energy. These pools can be found deep underground and are typically used for geothermal energy production or natural hot spring bathing.
Billiards.
pool, lagoon
A geothermal underground pool is typically referred to as a hot spring or a thermal spring. These pools are naturally heated by underground geothermal sources, such as magma chambers, and are enjoyed for their relaxing and therapeutic properties.
Pond, pool.
Genetic reservoir.
An underground thermal pool is called a geothermal pool. These pools are heated by geothermal activity deep within the Earth's crust, providing a natural source of warm water for relaxation and therapeutic benefits.
A kitty. A fund. A pot.
Another name for geothermal energy is ground source heat.
Geothermal energy is heat from the Earth.