The first kayaks were built about 5,000 years ago by the Inuit and Aleut people to help them move quickly across the water. These early kayaks were typically made from driftwood or whale bones that were covered in animal skins and coated in whale fat to help waterproof the craft. To increase buoyancy, seal bladders filled with air were attached to the boats. Kayaks were first used for sport in Europe in the mid-1800s, and kayak racing first became an Olympic event at the 1936 Games in Berlin. By the 1950s, kayaks were being manufactured using fiberglass, and today most kayaks are made from heavy-duty polyethylene plastics.