Catalina Island

Santa Catalina Island lies about 22 miles (35 km) off the Los Angeles coast, reachable by roughly one-hour ferries from Long Beach, San Pedro, and Dana Point, and is ringed by nine marine protected areas covering roughly 22 square miles of habitat. The signature dive is Casino Point in Avalon — set aside by the city in the early 1960s, established as the Avalon Underwater Park in 1965, and designated a 2.2-acre no-take state marine conservation area in 2012 — a staircase-entry shore dive through giant kelp (Macrocystis pyrifera) over rocky reef and small wrecks to about 29 m. Boat sites run from the gorgonian walls of Bird Rock and the Ship Rock pinnacle off Two Harbors to Farnsworth Bank on the exposed windward side, where California purple hydrocoral has been protected since 1972. Surface water runs roughly 13–15°C in winter and 21–23°C in late summer (colder below the thermocline, near 11°C in winter), so a 7 mm wetsuit or drysuit is standard for much of the year; visibility averages 9–12 m and peaks at 18–24 m or better from September through November, with spring plankton blooms sometimes dropping it to 6 m. Catalina is the heartland of the recovering giant sea bass (Stereolepis gigas, IUCN Critically Endangered) — a 2025 study estimated about 1,221 adults in Southern California with an increasing trend — and hosts the USC Catalina Hyperbaric Chamber at Big Fisherman Cove, staffed around the clock since 1974. Southern California's kelp canopies declined during the 2014–2016 marine heatwave with spatially patchy recovery, and cover at individual sites such as Ship Rock still varies from year to year.

• Casino Point was established by the City of Avalon as the Avalon Underwater Park in 1965 — one of the first dedicated underwater parks in the United States — and was designated a 2.2-acre no-take state marine conservation area by the California Fish and Game Commission in 2012; cement staircases lead straight into kelp forest with visibility up to 24 m in late summer and fall.
• Farnsworth Bank, on Catalina's open-ocean windward side, holds Southern California's best-known stands of California purple hydrocoral (Stylaster californicus) — a brittle species that grows less than a quarter inch per year and has been protected here since a predecessor conservation area was established in 1972 specifically to prevent its collection; the bedrock pinnacles peak near 15 m and plunge toward a seafloor deeper than 1,900 feet within the two Farnsworth SMCAs.
• The first direct population assessment of the Critically Endangered giant sea bass (Marine Ecology Progress Series, May 2025) used more than 1,600 community-sourced photos and spot-pattern matching to estimate roughly 1,221 adults in Southern California from 2015–2022, with mark–recapture models indicating an increasing trend — evidence that California's fishing moratorium, in place since 1982, is working. Catalina is a core study and encounter area.