Photos by #ronan_donovan // Two adolescent male mountain gorillas - Ubwuzu, 11, and Agahebuzo, 10 - grapple in a playful embrace on the slopes Mount Karisimbi in Rwanda's Volcanoes National Park. These two 300lb giants tussled for 10 minutes, taking short breaks between bouts to catch their breath. The elevation and moving those large bodies left them both breathing heavily. This is an unpublished image series from my article in the current issue of National Geographic Magazine titled The Gorillas Dian Fossey Saved, written by Elizabeth Royte. Hop over to #ronan_donovan to see the full photo sequence of these two gorillas playing.