Venado Caves look difficult. I really wanted to try this, but even I have my limits with my 3 and 5 year old.
I put a link so you can see a video on the whole process of the caves. I just did not want my kids to freak out on two different excursions, so we did the zip lines (the loved it). I thought there was too much danger (and there was an age limit).
I am not too sure about the birthing hole you have to squeeze through. That made me anxious on the video. I do not think I could sell my wife on paying to: get excessively dirty, crawling around on wet (God knows what made it wet), muddy, rocky surfaces in which she could not see anything. I did not even get to the part where they are blind fish and other goodies (insects/snakes) that roam around and you bump into.
Also, I did not not tell her about the cave spiders. Yeah these ones have pinchers and arms, they are QUITE BIG!!!!
So after all that I thought I would save that trip for later.