Native people made many types of boat for different purposes.The baidarka, developed by indigenous cultures in Alaska, was also made in double or triple cockpit designs, for hunting and transporting passengers or goods.Most of the Aleut people in the Aleutian Islands eastward to Greenland Inuit relied on the kayak for hunting a variety of prey—primarily seals, though whales and caribou were important in some areas.Skin-on-frame kayaks are still being used for hunting by Inuit people in Greenland, because the smooth and flexible skin glides silently through the waves.These first kayaks were constructed from stitched seal or other animal skins stretched over a wood or whalebone-skeleton frame.(Western Alaskan Natives used wood whereas the eastern Inuit used whalebone due to the treeless landscape).This section may require cleanup to meet Wikipedia's quality standards.
The paddler's body shape and size is an integral part of the structure, and will also affect the trade-offs made.
Rotomolded plastic kayaks first appeared in 1973, and most kayaks today are made from roto-molded polyethylene resins.
The development of plastic and rubberized inflatable kayaks arguably initiated the development of freestyle kayaking as we see it today, since these boats could be made smaller, stronger and more resilient than fiberglass boats. The kayak is floating too high, it is too wide for his hips and shoulders, and it is so deep that his elbows hit the deck. It is impossible for him to paddle efficiently, and he will tire quickly.
Some modern boats vary considerably from a traditional design but still claim the title "kayak", for instance in eliminating the cockpit by seating the paddler on top of the boat ("sit-on-top" kayaks); having inflated air chambers surrounding the boat; replacing the single hull by twin hulls, and replacing paddles with other human-powered propulsion methods, such as foot-powered rotational propellers and "flippers".
Kayaks are also being sailed, as well as propelled by means of small electric motors, and even by outboard gas engines.