Lost Arrow Spire is a detached pillar in Yosemite National Park, in Yosemite Valley, California, located immediately adjacent to Upper Yosemite Falls. The structure includes the Lost Arrow Spire Chimney route which is recognized in the historic climbing text Fifty Classic Climbs of North America. The spire is the location for a dramatic and famous Tyrolean traverse, which has since become an equally notable slackline.