Morty,

I have an irrational fear in certain situations of heights, but all heights don't bother me.   Airplanes, tall buildings, or overlooks with sturdy rails don't bother me - it is more like fear of walking across things like swinging bridges, railroad trestles where there are those big gaps between the ties, or walking on a wall or path with a little height to it that is exposed on both sides. There has got to be some somewhat realistic, even though remote possibility of falling off, (or getting run over by a train), but my reaction is phobic and out of proportion to the danger. I'll swim or wade a creek in winter before I will cross it on a fallen log, even if the drop is only 4 feet. (On the occasions I have actually fallen of the log or slipped off rocks while jumping from stone to stone across a creek, the fear completely dissolves for the rest of the hike, but is there just a strong on the morrow.

Climbing trees, back when I was strong and agile enough to do so, didn't bother me a bit.

Go figure.