ABC News' John Donvan reports:
Meet Sue Austin, a real-life "mermaid."
She began experiencing rare neurological problems 16 years ago after contracting cytomegalovirus and eventually lost all her mobility.
It bothered Austin of Devon, England, to be perceived by others as limited and confined because of her wheelchair.
"It was as if they couldn't see me anymore, as if an invisibility cloak had descended," Austin said during one of her TEDTalks, which has been downloaded by more than half a million people.
So Austin went to the sea to show the world the device she rides in a whole new way. She has a double set of propellers on the back of her wheelchair that allow her to soar underwater.
"I literally have the freedom to move in 360 degrees of space and an ecstatic experience of joy and freedom," she said.
But the technology behind it took a little doing.
"I started talking to engineers and they said, 'No you're not going to be able to do it,'" she said. "Which was probably the best thing that anyone could have said to me."
With the help of fellow divers, Austin invented a wheelchair with propulsion thrusters, custom fins and an air tank. Then, she took her first plunge on a ride that no one had ever taken before.
"I now call the underwater wheelchair 'Portal,'" Austin said. "Because it's literally pushed me through into a new way of being, into new dimensions and into a new level of consciousness."