The roll is an essential for paddlers who attempt serious whitewater (Class IV or greater), as exiting the boat and swimming gives the paddler less maneuverability and control, and thus leaves them more exposed than in the boat.
A kayak-mounted video of a roll in a pool
A kayaker surfaces at the end of a roll on whitewater
Kayaker coming up from a roll on flat water
The skill of righting a capsized kayak was devised by the hunter-gatherer societies that also developed the kayak as a hunting boat; the Aleut and Inuit people. The Greenland Inuit used several techniques that allowed the kayak to be righted with or without a paddle, also using only one hand, or without hands at all. A survey in Greenland in 1911 found that of a total of 2,228 hunters with a kayak of their own, 867 were able to roll.