Lava River Cave is a lava tube in northern Arizona's Coconino National Forest. At approximately 0.75-mile (1.21 km) long, it is the longest cave of its kind known in Arizona. The cave was discovered by some lumbermen in 1915 and has historically been referred to as "Government Cave" due to its location on the eastern edge of Government Prairie and southeast of Government Peak. Today, Lava River Cave is freely accessible to the general public.