A raft is a flat object used for support or moving across water. It usually does not have a hull. Rafts stay afloat using materials like wood, sealed barrels, or inflated air chambers (like pontoons). They usually do not have engines to move them. Rafts have been used for a long time. Natural rafts made of tangled plants and wood have helped people cross water since the beginning of human history.

Human-made rafts

Traditional or early rafts were made from wood, bamboo, or reeds. Early float rafts used inflated animal skins or sealed clay pots, which were tied together. Modern float rafts may also use pontoons, drums, or polystyrene blocks. Depending on their purpose and size, rafts may have additional parts, such as masts, rudders, or other structures.

Timber rafting is a method used by the logging industry to move logs by tying them together into rafts and floating or pulling them down rivers. This method was used often until the middle of the 20th century but is now used very rarely.

Large rafts made of balsa logs and using sails for navigation were important for trade along the Pacific Ocean coast of South America from before European arrival until the 19th century. These rafts traveled as far as Mexico. Many modern trips across the Pacific Ocean have used replicas of these ancient rafts to show possible connections between South America and Polynesia.

Rafts used for recreation are mostly inflatable rafts made from flexible materials like PVC, hypalon, polyurethane, and nylon. These materials help the rafts withstand bumps and rough use in fast-moving water. Whitewater rafts are designed with a high rocker, meaning the front and back are raised, which helps them move over waves and obstacles. Most rafts also have drain holes in the bottom to keep water from filling the boat.

Natural rafts

In biology, especially in the study of island biogeography, natural rafts play an important role. These rafts are made of tangled groups of plants that are carried from land into the ocean by events like storms, tsunamis, tides, or earthquakes. In recent times, these rafts may also include other floating objects, such as plastic containers. They stay on the water because of their natural ability to float and can travel hundreds or even thousands of miles. Eventually, they are broken apart by waves or decompose, or they reach land.

Rafting events help animals move across the ocean. For amphibians, reptiles, small mammals, and many invertebrates, these floating vegetation groups were often the only way they could reach and, if they survived, settle on oceanic islands. This was especially important before human-made vehicles provided other ways for animals to travel.