3 Roald Amundsen
Roald Amundsen was Norwegian explorer best known for his explorations of both the North and the South Pole. For that, he is considered one of the most successful if not the most successful explorer of the 20th century.
He went to history as a hero as he set out with a small party aboard the plane to search for members of a crashed airship. It was on this mission that Amundsen and his crew vanished without a trace.
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4 Oscar Zeta Acosta
Oscar Zeta Acosta was an accomplished author, dedicated Chicano activist and successful attorney. And although he didn't become the sheriff of Los Angeles county he still managed to receive 100,000 votes in the process.
While traveling in Sinaloa, Mexico, Costa allegedly phoned his son just before disappearing and his location has never been determined.
According to some sources, he was an amfetamine addict, which may just very well be the cause of his disappearance.
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5 Jim Gray
Jim Gray, an award-winning computer scientist, is best known for his contributions in the field of database and transaction processing.
On January 28th, 2007 Jim Gray set sail aboard his yacht to scatter his mother's ashes near Farallon Islands off San Francisco. But California emergency location beacons were never activated and no trace of him or his 40-foot yacht was ever found.
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6 Henry Hudson
Henry Hudson was one of the greatest English explorers during the Age of Exploration. He is the namesake for the Hudson River and Hudson Bay. And his everlasting wish was to find Northwest Passage to China. But he was two times unsuccessful.
After a small break, he wanted to pursue his quest but his crew disagreed and rebelled.
The crew eventually set Hudson adrift on an open boat along with his son and seven crew members. Since then he was never seen or heard again.
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