freediving; free-diving
Underwater diving without breathing apparatus, relying on breath-hold. Often used in sports and recreational contexts.
See also: 素潜り
He holds the world record for freediving.
Similar to freediving but often implies shallower, more casual breath-hold diving, sometimes with basic gear like mask and fins. The distinction from freediving is subtle and may overlap in common usage.
I enjoyed skin diving in Okinawa.