The second-oldest public aquarium in the United States, this classic attraction dates back to 1904 and has amassed 3,500 marine animals since then. The emphasis remains on aquatic life in the Pacific, including seahorses, giant clams, and deeply endangered monk seals, as well as propagation of corals like the rare Montipora dilatata. A 7,500-gallon tide pool offers a hands-on experience where you can interact with tropical fish, sea urchins, and tubular sea cucumbers. Once a month—tides permitting—the aquarium is open for visitors to explore nocturnal activity by torchlight. Water babies will especially appreciate the aquarium’s box jellyfish calendar online, which charts when the fierce, stinging animals are most likely to surface in shallow waters alongside swimmers, snorkelers, and divers.