Answer:
Isolation.
Step-by-step explanation:
One disadvantage of natural barriers is isolation. For example, if a group of people are living on an extremely small island in the middle of the Pacific Ocean, with lacking resources and a non-sturdy dinghy boat, the Pacific Ocean is serving as a natural barrier that isolates the group of people. Due to their lacking resources and nearly non-existent means of escape, this isolation is not at all beneficial.