Come dive the annual Catalina Clean Up. We will book your Catalina Express ticket for you. USC?s Catalina Hyperbaric Chamber and Wrigley Institute for Environmental Studies?Catalina Conservation Divers are proud to host Catalina Island?s 38th Avalon Harbor Underwater Cleanup, one of the largest annual dive events in Southern California. The event began in the 1970s in an effort to cleanup Avalon Harbor, and this event is the only time diving is permitted in the Harbor.