This is a very small aquarium with very good displays of local sealife. The website indicated the entrance fee for adults is $5.00 but when we went, they just asked us to make a donation (any amount was good). Call ahead and find out what time low tide is and combine the visit with seeing the tidepools. It is truly fascinating. I'll write another tip about the tidepools so make sure to read up on that, too!
Pack a picnic and have that on the beach or on any of the grassy areas next to the parking lot. Parking is not free, you will pay according to how long you stay.
Combine your visit with the Cabrillo Marine Aquarium which is only about 10 minutes walking distance. Call ahead to see when it is low tide. Park in the parking lot of the aquarium. Watch your time because parking is charged by how long your stay is. The tidepools are really fascinating! You can find small crabs everywhere. Hermit crabs if you look really hard. Sea urchins, sea anenomes, sea slugs, mussels, lots of kelp and sea shells. And, climbing your way about is fun, too! The cost to see the tidepools is FREE! Great activity for the kids.
This small aquarium in San Pedro is definitely worth a visit. Although it displays are a little antiquated, it offers a chance to get up close with some species that not common even in larger aquariums.