Thank you all for your responses. I feel much better about taking this trip. I never realized I had a problem until my husband and I went to Ruby Falls in GA. It is a 100 foot water fall in a cave. What they don't tell you is you practically have to go spelunking to get there.
I was fine when we got to the falls, but getting there was iffy. From the sound of everyone, this trip will not be a problem for me.
Terrapin, I think I will stick with the zoo. I am old, fat and out of shape. I don't need any more adrenaline.