Where may I store my luggage

We are disembarking in San Diego between 7 and 9 a.m. our flight is not until 9 p.m., the airline won't let us check in our bags until 3 p.m.. We want to spend the day at the San Diego Zoo, any thoughts on where we may store our bags would be very helpful.

Rent a car.

Several of the airport car rentals pick up from port. From experience I know Budget and Hertz do.

The zoo has lockers for luggage.