The Cannonball is a double grab where the skater grabs their board with both hands while in the air.
Unlike the other double grabs, the cannonball is very specific.
The skater must grab with both hands on the nose and the tail. In a normal double grab the skater can grab the board any way they want as long as they do it with both hands.
This trick is almost exactly like doing a cannonball into the pool. It’s super fun and makes a big “splash!”