Tsunami and Surf Waves

 Tsunami 

A tsunami is a series of waves caused by earthquakes or undersea volcanic eruptions. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases.

Surf Waves 

The surf is what you see when you stand on the beach and look at the ocean waves rising and breaking on the shore. It's also what you do when you ride those waves. Surf means "crashing waves," but it's also a verb meaning to ride those waves with a surfboard.