Do you know the difference between an island and a key? An island is created through geological processes such as volcano eruptions, and keys are made through biological processes like several organisms building a coral reef over time. Tens of thousands of years ago, south Florida was actually comprised of coral reefs. As the years passed and the sea levels dropped, the coral reefs died and eventually formed into limestone, which is a type of rock made of calcium carbonate. That’s why if you try to dig down anywhere in South Florida, you’ll eventually hit limestone. Here in Biscayne National Park we protect the northernmost of the Florida Keys. I recently visited Boca Chita Key in which I was able to go to a specific part of the key that had small tide pools.