Question

At last, it's time to go diving! You load your stuff into the boat and head to an offshore dive site.

Answer 1

A. The boat uses an engine which provides it the kinetic energy to move. The engine uses gasoline, or manual paddles, push pole or propeller.  
B. In terms of thermodynamics law- for every action, there is an equal and opposite reaction. In this case, the thrust causes movement in case of the boat.