Grizzly Man, documentary about Timothy Treadwell, lunatic or visionary who lived cheek to jowl with grizzly bears in Alaska for 13 summers claiming to be protecting them from poachers, hunters, the Park Service etc. Directed by Werner Herzog
I think I have a lower opinion than Herzog on Treadwell. He seems to be a complete egotist, filled more with a sense of his own importance than anything else. The fact is that he probably endangered the bears as they were desensitised to humans, making them easier targets for any poachers, although very few bears are poached in Alaska. His ranting about how he hated the human world was classical egotism - he was a failed athlete and actor who seemed pretty pissed off that he hadn't done anything that matched with his inflated opinion of himself.
Some of the footage of the bears themselves is absolutely breathtaking, including an amazing fight scene between two males - youtube link here. Treadwell seeme dto think of himself as a bear and tried to remove himself from the 'peoples world' into the bear world.
This ended when he, and his girlfriend, were killed by a grizzly in his 13th summer. He had previously left but returned after becoming frustrated by a sdispute at the airport. His girlfirnd wanted to leave but they were attacked by a bear and killed before she could.