Subway Cave in California is a lava tube located in Lassen Nationsal Forrest at road 44/89 north of the Old Station Visitor Information Center. It was formed in the Hat Creek lava flow, less than 20,000 yeas ago. This lava flow contains several lava tubes, but Subway Cave is the largest known.

Subway Cave is entered on a stairway at a place where the former roof collapsed, called Devil's Doorway. Beyond is a small widening of the tunnel is called Stubtoe Hall. From there it becomes rather narrow until Lucifer's Cul-de-Sac turns off to the left side. A wider passage goes to The Sanctum, the biggest chamber of the cave. The last part is called Lavacicle Lane, and is narrow again. Subway Cave ends at a collapse of the ceiling called Rattlesnake Collapse.