For early explorers, it was the ultimate survival contest; for researchers like me, it remains a place of great intellectual challenge; while for the modern tourist, it's simply a wilderness of great beauty.
The British explorer Wilfred Thesiger crossed it in the mid-20th century and he said it was named Rub al-Khali or " Empty Quarter" because it's so enormous and so desolate.
When I first learned about caravels, which were those small ships that Portuguese explorers used to travel down the African coast in the 15th century, I had a hard time remembering that name – caravels.
Spanish explorers claimed to see: " Cities that glistened in white." " Great quantities of maize and oats." " A town of disproportionate size… " " and a chief with gold idols… and other riches" .
That's more than six miles below the waves and it's only 63 feet shallower than what's believed to be the world record depth that was reached by an American explorer last year.