In 2002, Wim Hof swam more than 188 feet beneath three feet of ice in sub-zero water wearing only a bathing suit and goggles to clinch a spot in the Guinness Book of World Records.
Why goggles? Because in an earlier record-setting swim, Hof had almost died after having difficulty finding the exit hole -- because his retinas had frozen solid.
[Focusing requires that the shape of the retina (which acts like a lens to focus incoming light on rods and cones at the back of the eye) be changed by a series of tiny actuator muscles.]
Sources
"Guinness Primetime"; Guinness Book of World Records
