Skippy, take a lesson from the Native Americans when it comes to breaking a horse, lead the horse into the water until it reaches its belly, then hop on & keep it from reaching the shore. Since a horse has to lower its head to buck, you have the advantage of making it swim about until it no longer resists your authority, then allow it to swim ashore. If it tries to lower its head to buck, keep its head up to prevent bucking. With this advice I add a caveat, you may have to repeat doing this again to get you point across.
Skippy, take a lesson from the Native Americans when it comes to breaking a horse, lead the horse into the water until it reaches its belly, then hop on & keep it from reaching the shore. Since a horse has to lower its head to buck, you have the advantage of making it swim about until it no longer resists your authority, then allow it to swim ashore. If it tries to lower its head to buck, keep its head up to prevent bucking. With this advice I add a caveat, you may have to repeat doing this again to get you point across.