Biscayne National Park

Biscayne National Park was established in 1968. It is in Florida State, only 50 kilometers from Miami. Its area is 70000 hectares. 95% of the park is on water.
There are 42 keys (small islands) in this park. These islands were formed over millions of years. Over a long period of time, the sea level rises and falls. This is because, during colder periods the ice caps at the North and South Pole get bigger. This uses up water, and the level of the sea falls. During warmer periods, the ice caps melt and the sea level rises. When the sea level was much higher, coral grew underwater. When the sea level fell, the coral died and that created the ‘keys’.
The keys were made from coral. Some years ago people thought, coral is a plant, but now we know, coral is a tiny animal. It grows very slowly (1cm/year). That is corals and all the Biscayne national p