[Blades]

In Tora-Bora, in the river, just below the spot where you find the rifle, there is a "pit" in the river. At the bottom is a tin of catnip and a health pipe. (this is not the health pipe at the mouth of the river) When I first fell into it I thought it was another random collision problem, since normally you aren't supposed to sink through floors.

Anyone else found any equally hard to find secrets?
(Not including useless things like blowing up the pipe outside the back of RWS headquarters, hopping onto the roof and jumping off the edge of the world, literally)