San Diego-La Jolla Underwater Park Ecological Reserve an ocean wonderland

It is the only San Diego city park without park benches, water fountains, and walking paths. There is grass but it's nothing like Bermuda. Oh, and most who frequent here sport gills, not lungs.

This unusual place is the San Diego-La Jolla Underwater Park, which comprises 6,000 acres of submerged lands bordered by Torrey Pines State Park to the north and La Jolla Cove to the south. Within the park are 533 acres designated as a “look but don’t touch” reserve. At just over 1.5 square miles, the La Jolla Ecological Reserve comprises the waters around the Cove, the seven caves, La Jolla Shores, and the La Jolla Submarine Canyon. Five large yellow buoys mark the reserve’s offshore boundaries. Signage by the California Department of Fish and Game clearly states that “No person shall disturb or take any plant, bird, mammal, fish, mollusk, crustacean, reptile or any other form of plant life, marine life, shells, geological formations, or archaeological artifacts...” In short, no-take means anything and everything, living or not.

La Jolla’s underwater reserve is unique to the coast because it harbors four distinct habitats akin to land-based sisters known as the Grand Canyon, a redwood forest, a desert, and a bouldering area. And as with diverse land environments, the different marine habitats are a haven for diverse life as well. To learn more, follow along on an armchair tour of the reserve.

La Jolla Cove: Gateway to rocky reefs and kelp bed

We begin at La Jolla Cove, one of two gateways to the reserve. Likened to a public aquarium, you may take one step into the drink, and be surrounded byl zebra perch, señorita, and opaleye fish—all in depths of less than 10 feet. The outcropping of rocks and boulders supports a giant salad bowl of attached brown, green, and red algae that giant kelpfish have evolved to match in shape, color, and pattern. Verdant surf grass strands do a languid hula in response to the surge. California’s state marine fish, the flamboyant orange garibaldi, is notorious, as is its juvenile form, which sports electric-blue spots and streaks against a lurid orange background.

Continue out past the Cove to depths of 30 feet to reach the kelp bed. From land, it looks like a brownish surface slick. Made up of California giant kelp (Macrocystis pyrifera), which can grow up to 2 feet per day, the strands may soar to over 100 feet tall in deeper water. Here is where the giant kelp’s analogy to a towering redwood forest is fully realized. The reserve’s kelp stand offers grandeur nonetheless. Dive down amidst the tangled strands, then look up to see the fronds swaying gently in the surge, while shimmering rays of sunlight bend and splay against the amber fronds.

Kelp is somewhat of an anomaly in that it is a living substrate. As such, it is a living habitat, providing substrate for millions of animals from hundreds of species to find food, hide from predators, rest, reproduce, and bear young. There’s a heavy weight of responsibility on the fronds of giant kelp. Look on or near any part of the kelp and there is life. Harbor seals, the occasional 100-plus pound giant sea bass, bat rays, and schools of anchovies, barracuda, and señorita hover or weave through the forest. At its base, a stand of kelp is anchored by a holdfast, a complex maze of rootlike matter that binds itself to a rock or boulder. The holdfast houses a menagerie of small animals, like brittle seastars, young anemones, and insectlike isopods. Ocean floor that is sheltered by a kelp forest crawls with crabs, sea hares, sea fans, and knobby sea stars.

La Jolla Shores: Gateway to sand flats and submarine canyon

Across the bay from the Cove is La Jolla Shores, a mile-long beach and the reserve’s other gateway. Underwater topography here comprises shallow, ripply sand bottom. At first glance, this habitat looks like a desert wasteland but is instead flush with life, albeit more subtle than the dramatic displays found in the rocky reef and kelp habitats. For starters, find pipefish camouflaged in tufts of sea lettuce algae, and sea pansies, sea pens, and sand dollars dotting the sand’s surface or partially buried under the grains. During summer, see large groups of leopard sharks (Triakis semifasciata) congregating along the surf zone in depths of 3 to 7 feet, often at the southernmost end of La Jolla Shores beach.

Recent studies show these to be nearly all adult females. A leopard shark’s body (no more than 5 feet long) is adorned with thick black, elongated spots that drape over its gray back and sides. No need to worry about being confused for bait because a leopard shark’s dinner bell chimes nearly predominantly for squid, though clams, octopi, crabs, spiny lobsters, and bony fish may due in a pinch. For best viewing, snorkel or float on the surface, as scuba tank bubbles and almost any human movement will terrify the shy creatures. Look also for shovelnose guitarfish rays, which often cohabitate with the leopards.

The La Jolla Submarine Canyon plunges to nearly 1,000 feet (300 meters) deep and so is mostly off-limits to humans. However, scuba divers can investigate the numerous terraced ledges found at depths of about 50 to 85 feet, which harbor riches of the canyon’s marine life. To access the canyon, enter the water at La Jolla Shores. Swim west a couple hundred yards, after which the sandy bottom drifts downward, then drops off sharply, signaling entry into the canyon. Journey along the edge of the canyon, and you will pass over gently sloping areas, gullies, steep cliffs, and wide valleys. Oddly named and even odder-looking creatures like sarcastic fringehead fish, fairy hydroids, giant sheepcrabs, lion’s mane nudibranchs, and vermillion rockfish are some denizens of the canyon but other extraordinary creatures periodically emerge from the inky depths.

During winter, thousands to millions of market squid, Doryteuthis opalescens, may converge to spawn, which presents a breathtaking spectacle. In past years, the canyon has supported a football field of the squids’ cigar-shaped and sized white egg capsules, transforming the mud bottom into a winter snow scene. Commercial fishing outside the reserve has generally led to more modest shows in recent years.

​Stewardship—enjoy now and into the future

The San Diego-La Jolla Underwater Park Ecological Reserve affords protection to marine life dwelling within four distinctive landscapes, safeguards the area’s fragile ecology, and preserves the natural beauty of the shoreline. Even if you don't swim, snorkel, or scuba dive, you can directly experience at least a part of this unique city park by strolling the sandy beach, exploring a rocky tide pool, or canvassing the scene cliffside. Dare to don a face mask and take the plunge. The reward is discovering a wonderland of unparalleled beauty you otherwise could not imagine exists.