Really. If you ever got walloped by a wave you know they pack a punch. Here's why.
Water weighs 64 pounds per cubic foot and there are 27 cubic feet in one cubic yard. So a cubic yard of seawater weighs 1728 pounds. The original VW Beetle weighed only 1650 pounds!
If that seems hard to believe, consider that 1 cubic foot is almost 7.5 gallons, and a cubic yard is more than 201 gallons. Kowabunga!