Gull Island

Gull Island is a small rock island a little more than a mile offshore from the south-central coast of Santa Cruz Island, on the side that local boats call the back side. The dive site wraps the island itself and the shallow reef chain that runs out from it, with depths from about thirty feet on the kelp tops to ninety on the sand floor between structures. The island carries one of the largest shallow-water outcrops of California purple hydrocoral on the coast, with the pink and lavender colonies thick enough to dominate sections of the reef at thirty to fifty feet.

The hydrocoral is the headline. Purple hydrocoral grows in concentration at only a handful of California sites, most of them at offshore seamounts such as Farnsworth Bank off Catalina and Cordell Bank off Marin, and the Gull Island colony is among the largest that sit in recreational scuba depths. Lush giant kelp covers the shallower reef around the island.

Giant kelp anchored on the shallow reef around the island and growing up through the water column to the surface makes Gull Island a kelp forest biome. A rocky reef biome holds the bare structure between the kelp patches, including the hydrocoral-encrusted faces themselves, distinct from the kelp. The canyon biome is the vertical relief from the island's underwater base out to the open water, with the steep dropoffs to the deeper sand. Out past the reef edge, the seaward open water carries a pelagic biome where larger pelagic species transit through.

Access is boat only. Charter dive boats run to Gull Island from Ventura, Santa Barbara, and Channel Islands Harbor in Oxnard. The crossing is about two hours from Ventura, and the back-side run adds another half hour around the island's south coast. The site sits in open water on the southwest face of the island and is exposed to any south or southwest swell, which closes it on a building day.

Fishing and spearfishing are not legal here. The Gull Island State Marine Reserve covers the island, the surrounding reef chain, and a long stretch of the Santa Cruz coast to the south of it, with the matching federal reserve extending into deeper water. All take inside the reserve has been prohibited since the original 2003 designation. Standard California recreational rules apply only outside the reserve boundary box, which lies several miles in any direction from the dive site.