I’ve always found this one interesting:
At a young age it is possible to train your eyes to see underwater:
“Normally when you go underwater, everything is so blurry that the eye doesn’t even try to accommodate, it’s not a normal reflex,” says Gislen. “But the Moken children are able to do both – they can make their pupils smaller and change their lens shape. Seals and dolphins have a similar adaptation.”
The article says anyone is able to do it with practice, but as you age you loose the ability, even the kids in the tribe would.