Startups are building balloons to hoist tourists 100,000 feet into the stratosphere

Commercial space flight is becoming more and more common, with companies including SpaceX, Blue Origin and Virgin Galactic all transporting paid customers into space over the last several years.

People interested in seeing the earth from an unusual vantage point may soon have another option. CNBC spoke to three startups — France-based Zephalto, Florida-based Space Perspective and Arizona-based World View — that aim to hoist tourists to the stratosphere using pressurized capsules and massive gas-filled balloons.

"The capsule itself is designed to to carry eight customers and two crew into the stratosphere," said Ryan Hartman, CEO of World View. "There will be a center bar where people can gather, and then, of course, there will be a bathroom aboard the capsule."

The balloon rides will last around 6 hours, but will nottake passengers all the way to space. Most will reach heights of 15 to 19 miles above the earth's surface, flying in an area known as the stratosphere. The start of space is generally accepted by the U.S. government to be around 80 kilometers, or about 50 miles, above the earth's surface.

Jane Poynter, founder and co-CEO of Space Perspective, has a differing view.

"There is no universal definition of space," Poynter said. "We are regulated as a spaceship. If we go over 98,000 feet, we are a spaceship. Outside the capsule, it's essentially a vacuum. We're above 99% of Earth's atmosphere, which is why the sky is so deep black."

Compared to rocket-powered space tourism, the physical sensation that passengers will experience on a stratospheric balloon ride is more comparable to being on an airplane. Passengers will not experience weightlessness.

"We don't need any physical requirements to board the balloon," said