Complex sentence: Fiesta Key is an island in the Florida Keys, connected via causeway to U.S.1 (or the Overseas Highway) at mile marker 70, near the eastern end of Long Key.
Split into simpler sentences: Fiesta Key is an island in the Florida Keys. It is connected via causeway to U.S.1 (or the Overseas Highway) at mile marker 70, near the eastern end of Long Key.