Complex sentence: An unofficial extension known as the International Appalachian Trail continues north into Canada and to the end of the range, where it enters the Atlantic Ocean, whereas unofficial extensions heading south into Florida create what is known as the Eastern Continental Trail.
Split into simpler sentences: An unofficial extension known as the International Appalachian Trail continues north into Canada and to the end of the range, where it enters the Atlantic Ocean. Other unofficial extensions head south into Florida, creating what is known as the Eastern Continental Trail.