I wonder what he/she saw under the waters as it’s a great white territory chasing the sea lions especially birthing season coming up in a few months and start to gather or just the waves themselves running from 30-60 feet. Some times they’ll try to surf the smaller waves with the surfers and could knock them off their boards but usually don’t.
https://www.surfer.com/culture/california-sea-lion-hijacks-mavericks-jet-ski