What are three of the difficulties that Farquhar seems to overcome while he is in the stream?

First he manages
to get his wrists untied. Then he claws the rope away from his neck. He fights his way to the
surface and bursts out of the water breathing in great gulps of air. He then finds he must then
dive deep down into the stream to avoid being shot. Once again he fights his way to the surface
and emerges downstream and continues to swim along with the current in his apparent attempt at
escape.