Oh really, I might conquer this fear but I was once tried a in a natural cave in the Philippines but I just walked in less than 5 meters and felt something so I went out haha. Maybe if the are looks like this in your photos, I might get in too. Because that tunnel seem a manmade one.
If you have the chance to visit Philippines maam you can visit many beautiful natural caves there in Palawan and also in Negros Island. There are caves that the ceiling and the floor are covered with awesome form of stalagmite and stalactite. Mabinay Negros Oriental is a cave capital of the Philiipines, they believed there are 400 caves in the place.