Watch The Core for Free: How to Stream the Movie Online at 123Movies. . The Core delves into the life of legendary mountaineer, BASE jumper and all-around explorer Dean Potter. Set in the mecca of rock climbing, Yosemite Valley, California, the site of some of Dean's most notable climbs. It shows Dean Potter's lifestyle beneath the walls and includes his epic free climbing in a single day on Half Dome and El Captain , two of the most impressive and iconic big walls in the earth.