This is a good perspective to see just how these rafts flex during the heavy up-and-downs of these big rapids. The raft is essentially 4 segments consisting of a raft up front where passengers primarily are; a raft in back where a good bit of cargo, the boat crew, and motor reside; and two very large pontoons lining the sides and primarily attached to the front raft in regards to flexibility. See in this series of photos how the raft flexes through this rapid.

Colorado River, Grand Canyon.