33.9772°N, 120.1058°W.
Second-largest of the northern Channel Islands and a core component of Pleistocene Santarosae, the megaisland that fused San Miguel, Santa Rosa, Santa Cruz, and Anacapa into a single landmass during the last glacial maximum. Arlington Springs Man — human remains radiocarbon-dated to ~13,000 years before present (Johnson et al. 2002) — is one of the oldest confirmed Americans, recovered from a coastal canyon on the island's northwest. Santa Rosa carries one of only two natural Torrey pine groves left on Earth (the other is on the San Diego coast 300 km south, the two stands genetically isolated since the Pleistocene). The island's caliche forests — calcium-carbonate-lithified casts of buried Pleistocene root systems — record the moment vegetation calcified in place.
A wildfire ignited on the island 15 May 2026.