Birch Aquarium is a public aquarium in La Jolla, a community of San Diego, California. It serves as the public outreach center for Scripps Institution of Oceanography at the University of California, San Diego, with over half a million people visiting the aquarium each year.

The aquarium houses more than 3,000 animals representing over 380 species. The hilltop site provides views of La Jolla Shores and the Pacific Ocean. The aquarium is an accredited member of the Association of Zoos and Aquariums (AZA).

The aquarium was established in 1903 after the Marine Biological Association of San Diego was created to conduct marine research in the local waters of the Pacific Ocean (its name was later changed to Scripps Institution of Oceanography to honor supporters Ellen Browning Scripps and E.W. Scripps, part of the Scripps family of newspaper pioneers). The founders built and maintained the small public aquarium and museum to communicate their discoveries to the world.

The researchers outgrew their modest laboratory in the boathouse of the Hotel del Coronado and moved to a small laboratory at La Jolla Cove in 1905. Several years later, the association purchased 174 acres (70 ha) at La Jolla Shores for $1,000 at a public auction from the city of San Diego. The first permanent building at the new site, the Old Scripps Building, was constructed in 1910. Today it is listed on the National Register of Historic Places.

In 1915, the first building devoted solely to an aquarium was built on the Scripps campus. The small, wooden structure contained 19 tanks ranging in size from 96 to 228 U.S. gallons (360 to 860 L). The oceanographic museum was located in a nearby building.

The Scripps Aquarium-Museum was completed in 1950. Named to honor former institution director T. Wayland Vaughan, it opened in 1951 as the Thomas Wayland Vaughan Aquarium. The three-story facility served the institution for more than 40 years. A ring of 18 tanks, the largest at 2,000 U.S. gallons (7,600 L), surrounded a central museum of glass exhibit cases displaying Scripps research projects. Within a month of its opening, visitors from all 48 states had signed the guest book.

In 1985, the Stephen and Mary Birch Foundation started a fund-raising effort for a new aquarium by donating $6 million. UC San Diego donated the land. JCJ Architecture of San Diego was selected as the design architect, and in 1992, the current $14 million aquarium opened its doors, then known as the Stephen Birch Aquarium-Museum. Shortly afterwards, its name was changed to Birch Aquarium at Scripps. In March of 1996, the 40 ft (12 m) bronze whale statues "The Legacy" were unveiled in memory of Ted Scripps II. Birch Aquarium celebrated its 20th anniversary in September 2012 by introducing a new visual identity.

There is currently a proposition to expand the aquarium and its facilities throughout 2028.

At 64,157 square feet (5,960.4 m), Birch Aquarium is designed around a central lobby with entrances to exhibit areas. Display tanks contain 175,000 U.S. gallons (660,000 L) of seawater.

Hall of Fishes features more than 60 tanks of Pacific fishes and invertebrates. The path along the Hall of Fishes follows the currents of the North Pacific Gyre, starting with tanks inspired by the Pacific Northwest, then tanks with organisms from California, followed by tanks with organisms from Mexico and Baja California, ending with tanks inspired by the Indo-Pacific. The largest habitat is a 70,000-U.S.-gallon (260,000 L) kelp forest tank. The tank can be viewed live online through the Kelp Cam.

The Hall of Fishes was closed in September, 2024 for renovations and the development of a new attraction, called Living Seas. The new exhibit is planned to open in summer 2025 with digital displays, larger viewing windows, and a new orientation of Pacific fishes in 3 distinct sections: Pacific Northwest, Coastal California, and Tropical Pacific.

Just past the Boundless Energy courtyard, is ElasmoBeach. ElasmoBeach is a sandy bottomed outside tank based on the sea floor of La Jolla. This tank features various sharks and rays, including leopard sharks and pacific angelsharks.

Tide-Pool Plaza features three living tide pools where visitors can touch and learn about tide-pool animals with docents. Windows in the habitats provide up-close views of starfish, hermit crabs, sea cucumbers, lobsters, and other animals local to San Diego's tide pools. The tide pool overlooks La Jolla and the Pacific Ocean.

In this exhibit, Birch Aquarium promotes sea dragon conservation. In this exhibition you’ll find a multitude of fishes in the seadragon family such as seahorses, pipefish, sea dragons, etc. Birch Aquarium has focused on this species’ rehabilitation because of the impacts that climate change and poaching have on the ocean.

The exhibit features more than a dozen seahorse species and their relatives, a special seahorse nursery, and hands-on activities for all ages about seahorse biology. Birch Aquarium is a world leader in seahorse propagation, reducing the need for other zoos and aquariums to collect from the wild.

In March of 2023, The Birch Aquarium's seadragon conservation program successfully bred 70 weedy seadragons. The aquarium had previously bred two seadragons in 2020, however, the event in 2023 was the first occurrence inside an exhibit.

This unique place in the aquarium is inspired by a comic-book designed exhibit that displays the odd qualities of the ocean and its species. In collaboration with the Scripps Oceanographic Collections, they uncover the superpowers of aquatic creatures, ranging from armor to supersight to electricity and the inspiration it's offered to cinema, medicine, engineering, and more.

The Beyster Family Little Blue Penguins exhibit is named after the long-time supporters, Beyster Family, who generously gifted $1 million to Scripps Institution of Oceanography and Birch Aquarium. This exhibit features little blue penguins that live in an 18,000 gallon penguin lagoon that imitates the coast of Australia and New Zealand where the little blues live. It also includes a small amphitheater that allows guests to observe the penguins, as well as a “discovery cove” for children to get a closer look at these penguins.

This is an outdoor playground that celebrates the innovative ways we can use natural forces to power our lives. Interactive stations explore ways to harness renewable energy from the sun, the wind, and ocean motion. Visitors can expend their own "boundless energy" at a play area for kids in which stationary bikes, hand cranks, and a seesaw powers a whimsical water sculpture.

• Summer 2014 San Diegans vote Birch Aquarium at Scripps the Best Museum in San Diego in the annual A-List poll for the fourth year in a row.
• Summer 2013 San Diegans vote Birch Aquarium at Scripps the Best Museum in San Diego in the annual A-List poll for the third year in a row.
• Summer 2012 San Diegans vote Birch Aquarium at Scripps the Best Museum in San Diego in the annual A-List poll for the second year in a row.
• Fall 2011 San Diegans vote Birch Aquarium at Scripps the Best Museum in San Diego in the annual 10News.com A-List poll. The aquarium was voted the #2 museum in 2008, 2009, and 2010.

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  Entrance
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  Diamond stingray (Hypanus dipterurus).
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  Leafy seadragon (Phycodurus eques).
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  Leopard shark (Triakis semifasciata).
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  Little penguins (Eudyptula minor).
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  Star III submersible on display.
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  Seahorse
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  Sea jelly.
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  Zebra bullhead sharks (Heterodontus zebra).
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  Scripps Pier in front of the aquarium.

• Official website
• Scripps Institution of Oceanography
• University of California, San Diego