Even with stiff boots, some cavers have to use 3-inch wide webbing stirrups when ascending long drops. Non-marking soles are often desirable or required in caves where surfaces can be smudged. You can usually tell if a sole will mark by rubbing it on concrete. Unfortunately, some non-marking soles do not grip well. This is a situation where safety and conservation may have to be balanced.
Steel toes are available on some boots.
These offer more protection from impact but add weight, contribute to cold feet, and cause the material over the toes to wear faster. Low boots let mud and gravel in, but they are easier to put on and take off, and some feel that they allow more movement for technical climbing. Jungle boots have long been popular with cavers. They are tough, light boots with drain holes and fabric uppers. Unfortunately, most of them are now cheap imitations that have been known to fall apart on the first cave trip.