This underwater jetpack lets you swim faster than Phelps

The goal was an ambitious one: Create an underwater, “Iron Man”-inspired jetpack capable of propelling someone through water faster than Olympian Michael Phelps on his best day in the pool.

In the process, Ryan Kung and David Shulman, two Silicon Valley engineers behind “Eclectical Engineering” — a YouTube channel dedicated to bringing imaginative contraptions to life — knew they’d be embarking on their most dangerous project to date, a reality that did little to deter the duo.

Combining battery-powered motors and water is, of course, is a recipe for electrocution. That explains why the two men spent the bulk of their time figuring out how to create a watertight seal for the jetpack’s battery compartment, which contained powerful lithium batteries.

The sealed battery pack was initially tested in three feet of water. That meant the men couldn’t be certain the pack would remain water-resistant if the depth, and pressure on the pack, increased.

How did Shulman feel jumping into the water for the first time?

“It was absolutely scary,” he said. “This was really putting your money where your mouth is. I’ve never built a project and then strapped it onto myself before.”

As their finished YouTube video attests, Shulman survived, and the project was a complete success. At top speed, the underwater jetpack clocked in at 6.25 mph, breaking Phelps’ record of 6 mph. The propellers were more powerful than expected, Shulman said, noting that at times it felt as if they were “going to pull my arms off.”

The pair, who do most of their DIY engineering on the weekends, estimate they spent 60 hours and $1,000 to make the jetpack a reality.