Lost River Reservation is a protected gorge in Woodstock, New Hampshire, in Kinsman Notch between Mount Moosilauke and Kinsman Ridge. It is known for the Lost River, which disappears into a narrow glacial chasm partly filled with huge granite blocks, then flows beneath them before reappearing downstream and joining the Pemigewasset River. Covering 157 acres, the reservation preserves a striking landscape of hidden water, rockfall, and boulder caves. Stairs and a boardwalk allow close exploration of the main gorge, while additional trails extend elsewhere on the property, making it both a scenic destination and an accessible geological site.