Haunting final photo of swimmer, 22, swept away by raging waterfall in Yosemite as witness describes desperate attempt to rescue drowning man from national park's famed 600ft drop

A 22-year-old swimmer was swept away by a raging waterfall at Yosemite National Park, with a witness describing a desperate attempt to rescue the drowning man. The incident occurred at the park's famed 600ft drop.