Even in this 21st century, brave adventurers still accomplish impressive feats of globe-crossing travel as they pioneer new technology. Two Swiss pilots are taking turns flying around the world without fuel. Bertrand Piccard recently landed near San Francisco after a risky 62-hour flight from Hawaii aboard the Solar Impulse 2, a sleek propeller aircraft powered by the sun. "This is one of the most fantastic experiences of life I've had," he said after landing April 23 in California.

The effort, sponsored by partly by Google and the Omega watch company, is intended to show the importance of renewable energy and innovation. It's also breaking several world records, including the first solar flight across the Pacific Ocean and longest endurance flight by any pilot. Piccard and André Borschberg have been alternating in the one-person cockpit since taking off from Abu Dhabi, capital of the United Arab Emirates, in March 2015. Each man sleeps only 20 minutes at a time so he can monitor the plane. The solar plane has landed in Oman, Myanmar, China, Japan and Hawaii. The trans-Pacific leg two weeks ago was the riskiest part because there were no emergency landing sites. Borschberg plans to take off Monday from California n the next leg to Phoenix. Impulse 2 will stop in New York City on its way back to Abu Dhabi.

The carbon-fiber plane is relatively lightweight and resembles a toy glider, with long wings and a skinny body. Its wings, stretching wider than those of a Boeing 747, have 17,000 solar cells that power propellers and charge batteries. The plane runs on stored energy at night. "It's a miracle of technology," Piccard says. "Clean technologies can achieve impossible goals. And if you can do it in the air, then of course you can do it . . . in everyday life."

Pilot says: "The adventure continues. The story is not finished." – Bertrand Piccard

Flying speed: The cruising speed of 28 to 50 mph is highest when daytime solar rays are strongest.

Top altitude: 28,000 feet, lower than for most passenger jets