Last of the Great Unknown (2012) is a Documentary film that follows the story of Grand Canyon's hidden slot canyons, the canyoneers who systematically explored their drainages, and the secrets hidden deep within their walls. Currently, you can watch Last of the Great Unknown on Echoboom Amazon Channel , Apple TV Store, Google Play Movies, YouTube. Streaming availability may vary by country and platform over time. It has a user rating of 8.0 out of 10 from 1 votes. Fans of documentary movies may also want to explore similar titles below.