Stephen Fry treks through the rain forest to meet mountain gorillas in Uganda and says the journey was "worth every sobbing, gasping, aching step".
There are only about 700 mountain gorillas - which are critically endangered, and distinguished by their large skull, wide face, and angular nostrils - in the world.
Last Chance to See
is on Sundays at 2000BST on BBC Two. Stephen Fry and zoologist Mark Carwardine's quest to seek out endangered species continues with the Northern White Rhino in the next episode on 13 September 2009.