First there's Nadya Vessey, a New Zealand woman who was born with a condition that prevented her legs from developing. At age 16, Vessey had both of her legs amputated, and has relied on prosthetics since. But, several years ago, when Vessey was in her fifties, she was struck with the idea to get a dolphin-like tail, which would allow her to swim as she hadn't before. "I never had a fantasy to be a mermaid," Vessey told the Telegraph. "[But] a prosthetic is a prosthetic, and your body has to be comfortable with it and you have to mentally make it part of yourself."
Other adaptations don't require physical additions so much as manipulation. Daniel Kish, who spoke with Swain, lost his vision when he was a year old to a form of cancer that affects the eyes. Since then, he's relied on his own two forms of echolocation, which is commonly used by bats, dolphins and whales to get a sense of the surrounding environment. Kish seems to have developed his echolocation skills on his own, relying on two different types, according to Swain: