A team of explorers has set sail from the US for Spain in a 12-metre-long (40ft) reed boat, hoping to spend about two months sailing across the Atlantic.
The Abora III's crew is hoping the trip will take two months
They are trying to prove that Stone Age people crossed the ocean thousands of years before Christopher Columbus in the 15th Century.
Aymara Indians in Bolivia, who still use reed boats, built the new vessel.
It takes its inspiration from prehistoric European cave paintings dating back more than 10,000 years.
Surrounded by the modern New York skyline, the dozen-strong team put to sea in the seemingly flimsy boat made of reeds.
The German biologist leading the expedition, Dominique Gorlitz, argues that traces of cocaine and nicotine found a few years ago in the stomach of the ancient Egyptian pharaoh, Ramses II, were native to the Americas, so must have travelled to Africa by sea.
He says he is also hoping to overturn current thinking that says the prevailing Atlantic winds would have allowed ancient mariners to sail west to the Americas, but would have prevented them from returning home.