A turbo powered Beaver floatplane enters the water off dry land. The propeller is a variable pitch type, which means the blades can be turned to either pull the plane forward, or blow it back. As it rolls down the ramp, you can see the blades are nearly straight, then they switch to reverse to slow the plane's speed as it enters the water. You can see by the water in front that the air is going forward. After it is in the water, the blades are turned again, until they are pulling the airplane forward.