A very short-sighted person (eyesight abnormality resulting from the eye's faulty refractive index due to which the distant objects appear blurred) can see more or less normally under water.
"The Moken people of South-East Asia are able to focus underwater to pick up tiny shellfish and other food items [1]. Gislén et al. have compared Moken and European children and found that the underwater visual acuity of the Moken was twice that of their European counterparts.[5] This ability appears to be due to training rather than evolution or genetics.[6] This is due to the contraction of the pupil, instead of the usual dilation (mydriasis) that is undergone when a normal, untrained eye, accustomed to viewing in air, is submerged. [7]"
