Shanghai and San Francisco, two cities separated by an ocean and an 11-plus-hour plane ride. For now.
Thanks to some new tech developed by scientists at Harbin Institute of Technology, we might one day see high-speed passenger submarines.
Currently the underwater ships move at about 46 mph - slower than your car on the freeway. But plans for the hypersub involve "supercavitation."
Essentially, it's a tech that creates a pocket of air around the submarine. It eliminates the friction normally placed on the ship by surrounding water. So the sub would basically "fly" underwater.
While you may not have heard of supercavitation before, The Washington Post points out it's not new. During the Cold War, "The Russians ... developed torpedoes that travel faster than 230 mph using that approach."
Supercavitation actually exists in nature too. The mantis shrimp achieves supercavitation during this incredible quick punch. (Video via Earth Unplugged)
Estimates from the California Institute of Technology say a supercavitating vessel could even hit the speed of sound underwater.
Time reports, "That would mean crossing the 6,000-odd miles from San Francisco to Shanghai in just two hours."
But let's be real, the speed of sound is a big ask. What's more likely is simply a much faster submarine. That is, if scientists can remedy the problems of the past.
The Cold War-era torpedo had two quirks that would prove problematic for a passenger sub: One, it had to take off at a high speed. Two, there was no way to steer it.
The Chinese have reportedly addressed both problems with a special liquid membrane. According to the South China Morning Post, this man-made liquid would "reduce the water drag on the vessel at low speed" and "help with steering because, with precise control, different levels of friction could be created on different parts of the vessel."
But there's still one significant issue, according to the outlet.
The engines used in the Cold War-era torpedo were only meant for use between 11 and 15 km. If researchers see this as another form of civilian transport, that's not going to cut it.
A writer for Sploid says let's not forget this is a military project. "This could be extremely useful for travel-but also for the development of underwater weapons."
The U.S. knows that too. Back in 2009, it was reported DARPA was looking into supercavitation to transport small groups of Navy personnel.
The video contains images from Getty Images and One half 3544.