As the final bolt locked the circular metal door into place at the end of the nearly mile-long steel tube, the two dozen members of the WARR Hyperloop team, from the Technical University of Munich, jostled to find shade under a canopy. The students spent the next 20 minutes waiting anxiously as pumps sucked nearly all the air from the tube. They were the third and final team to get a run in the last stage of Elon Musk's hyperloop competition. The only criterion for winning? Speed.

When many people hear the word hyperloop, they think it's some sort of fixed product that Musk proposed five years ago. Rather, it's more a genre of transportation than a single invention. The basic concept calls for a passenger- or cargo-packed pod inside a nearly airless tube, zooming at high speeds thanks to minimal friction and air resistance. The details—whether and how to make the pod levitate, how to propel it, what shape it should be, and so on—are anyone's guess. Musk laid out some particulars in a 2013, but the people trying to bring this concept to life treat the white paper he wrote that lay out these ideas as a starting point, not gospel.

That drive to create and innovate is what brought 700 members of 25 teams from around the world to the SpaceX headquarters Sunday for the second annual SpaceX Hyperloop Pod Competition. To add to the tension, Musk stood among the students, next to the tube that his own aerospace company, SpaceX, built along the edge of its rocket factory in Hawthorne, near Los Angeles. He peered over the students' shoulders at a laptop screen as they ran through last-minute checks, seeming to enjoy getting involved.

Finally, with a loud countdown from three to two to one, all eyes turned to the big screen that relayed a camera view from inside the glossy white tube. (Hyperloop racing is not much of a spectator sport.) The speed display ticked up, and up, and up, lights flickering past as the pod sped down the tube, before hitting the brakes to avoid hitting the far end of the sealed tube.

“That was an amazing job,” Musk shouted over the cheers that erupted from the bleachers, packed with other students who didn’t get a chance to race, but still proudly exhibited their pod designs. “Two hundred miles an hour for a student-built pod is incredible.”