Thanks Chris and Joe.
Each of these images is of a different raft. There were several launched at the same time, but they spread out when going through rapids.
Each raft had eight paying customers with paddles. In the back is the professional rafter who tells them when to paddle like crazy and which side should paddle.
In the last shot it's the pro hanging out the back. He didn't fall; he was just using his paddle as a rudder. In that position, he was directing the raft to his right- and slowing it a bit.
Charlie