Boyden Cave, Show cave in Kings Canyon, California, United States.

Boyden Cave is a solutional cave in Mesozoic marble in the Giant Sequoia National Monument, Fresno County, California. Its mapped passages run 0.63 miles and hold stalactites, stalagmites, flowstone and rare shield formations. The entrance lies beneath the 2,000-foot marble walls of the Portals of the Kings, above the Kings River.

Boyden Cave formed in Mesozoic marble as a solutional cave, and the source documents record no discovery date or early development history. It lies in the Giant Sequoia National Monument of Sequoia National Forest, along the Kings Canyon Scenic Byway in Fresno County, just west of Kings Canyon National Park. Licensed guides have run regular tours from the last Friday in April to mid-November, and 0.63 miles of passage have been mapped.

Guided tours run from the last Friday in April to mid-November and pass named formations: the Pancake Room, the Upside Down City stalactites, Mother Nature's Wedding Cake flowstone, the Bat Grotto where bats sleep through summer days, and the Drapery Room with curtains, soda straws and helictites. The walk ends at a small subterranean stream.

Access to the cave requires climbing a steep trail beneath tall marble walls. Visitors should wear sturdy footwear, bring a jacket, and expect cool temperatures inside.

Boyden Cave lies in Kings Canyon, at 8,200 feet the deepest river-cut canyon in the United States. Its entrance opens beneath the 2,000-foot marble walls of the Portals of the Kings, above the Kings River. About 0.63 miles of passage have been mapped, and tours run from the last Friday in April to mid-November.