Dylan Greiner, 38, owner and operator of Santa Cruz Surf School, is being detained on two counts of lewd and lascivious acts with children, the Santa Cruz Sentinel reported during the weekend.
He is accused of making inappropriate advances to two teenage students at his school.
While executing search warrants Friday, police found a collection of videos secretly recorded by Greiner of young girls changing into wet suits in dressing rooms at his business, Santa Cruz Deputy Police Chief Steve Clark said in a statement.
"They also uncovered a multitude of photographs and other video secretly recorded by Mr. Greiner where he purposely focused on breasts, buttocks and genitalia of young girls," Clark added.
The girls in the videos were as young as 8 to 10 years old.
Greiner became a local hero last year when he organized a campaign to rid local beaches of needles and trash.
He is being held on $500,000 bond. Additional charges are expected as police go through the more than 1,000 videos and photographs, Clark said.
Police believe Greiner may have been involved in the inappropriate activity for the past four years.