Waving back is the polite thing to do.
This is why you shouldn't go that close to the beach with your boat.
A stream near a beach gets dammed by the sand each year, building a reservoir of millions of gallons of water. By digging a trench in that sand, these guys create great waves of fresh water rushing into the ocean.
This guy is nuts. Look at the size of the wave he is surfing on.
Check out footage by restaurant patrons of a giant rogue wave crashing through the glass windows as they eat.
Footage of an Iceberg rolling over.
It was either that or get rolled over. He must be sore after that landing.
Paddling On The Crest of a Huge Wave