Rafts
A raft is any flat floating structure for travel over water.
Rafts are the most basic of boat design, characterized by the absence of a hull. Traditional or primitive rafts are constructed of wood or reeds. Modern rafts use durable, multi-layered rubberized fabrics.
Depending on the use of a raft and the rafts size, it may or may not have a superstructure, masts, or rudders. Rafts are kept afloat using any combination of buoyant materials such as wood, sealed barrels, or inflated air chambers.
The type of raft used nowadays for recreational rafting, also known as "whitewater rafting", is almost exclusively an inflatable boat, manufactured of flexible materials for use on whitewater.
You should go whitewater rafting - it is alot of fun!