Lake Wesson is an artificially made body of water that sits near the city of Leone. The lake was formed from a Pra'meth mining operation "accident" caused by a malfunctioning drill drone that released deposits of pressurized underground water to the surface and flooded some of the tunnels. However, the citizens of Leone know that the drill was actually sabotaged by Private Joseph Henry Wesson, a captive miner and former Ranger in the United States Army. The flooding killed most of the Pra'meths working at the mine but miraculously no humans died that day save for Wesson. The people of city named the lake in honor of his brave sacrifice.
12 years later, one of the caverns on a cliffside near the lake serves as the entrance to the underground base of Kamen Rider Nile. Inside the cavern is a hangar for the Rider Machines, a Panner to generate Soul Rounds, an elevator shaft, some of Nile's personal belongings such as her collection of antique books, graphic novels and movies, a medical bay and a worn out holographic simulator used for training.
The base was destroyed in episode 11 by Kamen Rider Khabur when he tricked the Riders into thinking he was an escaped prisoner of the Pra'meth bio-weapon testing grounds. He then transformed in front of them using his Rider Punch to critically damage the Panner and used his Prowl Axe to wreck the base and beat up the Riders before Pecos drove him away with Machine Sidewinder's guns.