Wikus and Heidi (1)
This photo shows why the guides went first. They positioned themselves along the banks and at the bottom to collect any people or belongings that flipped out of the boats.
Tubes said later that the water was at a very forgiving level: not one person and no equipment had to be rescued. Flip rates of up to 50% can happen.
In this photo, Tubes is holding his paddle straight up as Wikus and Heidi go down, signifying that everything is going fine (so far).