Tower Rock is a small, rocky limestone island on the Missouri side of the Mississippi River. Growing from the top of the rock is a small forest of beech, pine, oak and hickory. The rock has long been feared by riverboat captains because of the rapid current that swirls at its base, but when water levels drop, the island is easily accessed by walking over the dry limestone riverbed. Tower Rock was used as a navigational point for early explorers. It was visited by Meriwether Lewis and William Clark, with Lewis writing about this location in his journal over 200 years ago. In 1673, explorers Father Jacques Marquette and Louis Joliet stopped here during their travels to locate the mouth of the Mississippi River.