What's "turtle-ing"?
“Are his eyes that bad?”
“He is almost blind.”
“It is strange,” the old man said. “He never went turtle-ing. That is what kills the eyes.”
“But you went turtle-ing for years off the Mosquito Coast and your eyes are good.”

from old man and the sea
Ps: Doctor Rod tell me about the turtle hunt, now i need to know how it can "kill your eye" :)
I'm thinking about the effects of light reflection in the water after a long time trying to see a turtle, can someone confirm?

Thank you :)

Question

What's "turtle-ing"?
“Are his eyes that bad?” 
“He is almost blind.” 
“It is strange,” the old man said. “He never went turtle-ing. That is what kills the eyes.” 
“But you went turtle-ing for years off the Mosquito Coast and your eyes are good.”

from old man and the sea 
Ps: Doctor Rod tell me about the turtle hunt, now i need to know how it can "kill your eye" :)
I'm thinking about the effects of light reflection in the water after a long time trying to see a turtle, can someone confirm?

Thank you :)

Answer

It means to hunt and catch turtles. I don't know what method is or was used to do this.

Answer

Turtling in sailing refers to the situation where a boat overturns or capsizes, leaving its mast and sails submerged in the water. The term "turtling" likely comes from the resemblance of the inverted boat to a turtle on its back.