James Cameron: ~ $3 million, Deepsea Challenger

Canadian filmmaker and notoriously detail oriented director James Cameron has given us hits such as the Avatar series, Terminator movies, and Titanic. Of late, he has become an environmentalist, too and wanted to explore the deepest spot on Earth, the Challenger Deep at the bottom of the Mariana Trench. James piloted the $3 million specially built submersible vehicle, The Deepsea Challenger, and not only did the vehicle reach the seafloor, it explored the area for several hours, collecting samples and studying the topography.