"We are trying to retrace the ancient waterways to prove that prehistoric people crossed the ocean both ways," Gorlitz said at a news conference.
Scholars have expressed doubt about his assertions.
"There's this 99.9 percent certainty that it didn't happen because we don't have evidence that it happened," Kenneth L. Feder, an anthropology professor at Central Connecticut State University in New Britain, Conn., said in May. He is the author of "Frauds, Myths, and Mysteries: Science and Pseudoscience in Archaeology."
Gorlitz said traces of tobacco and cocaine were found in the tomb of Egypt's pharaoh Ramses II, evidence of long-distance trans-Atlantic commerce during the Stone Age. He also believes cave drawings in Spain show that people living 14,000 years ago had an understanding of ocean currents.