Counter Assault

All the literature says that the most effective bear deterrent is this stuff. Apparently you just spray it in the air between you and the bear and the bear wants NOTHING to do with it and runs the other way. Of course all the literature also says that if you're doing the right thing you'll almost never confront the bear in the first place. 

My first instinct would have been to bring a bazooka but that's apparently frowned on in the national parks. Friggen environmentalist hippies.