Staying at the Hyatt Regency in Huntington Beach. Looking for activities and restaurant recommendations in and around the area including Laguna & Newport. Two kids 10 & 14. Any good swimming holes?

https://ocbeachinfo.com/

Shows you the water quality at the various OC beaches.

Laguna has several good beaches. There is one just south of downtown in a residential neighborhood. Look for lots of cars parked on the street. There are steps down to the beach. I have never seen that beach real crowded even though it is small.
There are some decent eateries at the pier at Dana Point which is close to Huntington.