Subway Cave is off SR 89 about .1 mi. n. of SR 44. This lava tube winds 1,300 feet through a lava flow that covered the Hat Creek Valley nearly 20,000 years ago. Carry a jacket and a reliable lantern or flashlight while exploring the .3-mile self-guiding interpretive trail through this cave. The temperature in the cave is 46 degrees Fahrenheit year-round.