On their maps of the West, Lewis and Clark called it “the Great Unknown.”

For a one-armed geologist named John Wesley Powell, that was too much intrigue to ignore.

So in 1869, he led a team in four wooden boats on an expedition down the Green and Colorado Rivers, destined for what the Spanish called El Gran Cañon.

Within 2 weeks, a rocky rapid had destroyed one of their boats.

Within 2 months, most of their supplies were lost. Fortunately, the lightened boats rode higher in the dangerous waters.

Once in the canyon, the rapids echoed in a deafening roar. At times, the men climbed the walls to sleep in the relative safety of rock ledges.

At one point, the party was unable to portage their boats around a seemingly impossible stretch of rapids.

Three men refused to go further and tried to climb out of the canyon, while Powell and the others took two boats and pressed on.

Powell’s group made it through alive and signaled for the others to take the last boat—but the three men were never heard from again.

After 99 days, Powell and his remaining team reached their destination, but he had lost many of his records from the trip.

Unsatisfied, he returned 2 years later to do it again!

These remarkable journeys, as bold as Lewis and Clark’s Discovery Expedition, launched a movement to declare the Grand Canyon a national park.