Gardner Cave, Limestone show cave in Crawford State Park, Washington State, US.

Gardner Cave is a limestone cave in Crawford State Park in extreme northeastern Washington, 1,055 feet (322 m) long and the longest limestone cave in the state; the first 494 feet (151 m) are open to visitors. It holds stalactites, stalagmites, flowstone, pools and a column 2 feet in diameter, all formed in Cambrian Metaline Limestone.

Ed Gardner, a local bootlegger, claimed to have found the cave in 1899 when the ground collapsed beneath him and his horse; he stored moonshine there at a constant 39 °F. By one account he lost the deed to the cave and adjoining land to William Crawford in a poker game. In 1921 Crawford deeded the 40 acres containing the cave to Washington State Parks.

Ed Gardner stored moonshine in the cave because it holds a constant 39 °F (4 °C). The land passed to William Crawford, reportedly lost by Gardner in a poker game, and Crawford deeded the 40 acres with the cave to Washington State Parks in 1921.

Only the first 494 feet (151 m) of the cave's 1,055 feet (322 m) are open to visitors, and access is by guided tour from the Crawford State Park office. The interior holds a constant 39 °F (4 °C), so bring warm clothing, and expect slippery, uneven ground underfoot.

The seasonal lake lies near the Mud Room, the section farthest from the entrance, where several underground stream channels feed the cave. It appears only when that area is not completely flooded, so the water is absent for part of the year.