Wave Echo Cave is hidden among the Sword Mountains near Phandalin.
Description[]
The cave is rather appropriately named for the sounds of waves that echo through it. The cave is surprisingly cold. It has a portion nicknamed "jack-off tunnel" for the sound that the jelly monsters make when they are following the Tres Horny Boys.
Through jerk-off tunnel, one of the caverns has a deep spring well into which a drop of water falls from a stalactite, causing the unusually big waves after which the cave is named. Around the spring are fungi that release spores in response to noise. Above the spring is a wooden elevator.
Flora and fauna of the cave include said jack-off jellies, fungi, and several dwarf skeletons.
Also Magic Brian.