The ocean that borders California is the Pacific Ocean. This vast expanse of water significantly influences California's climate, economy, and ecology. The Pacific is the largest and deepest ocean in the world, providing California with extensive coastlines, beautiful beaches, and rich marine biodiversity. It supports a bustling fishing industry and is crucial for trade and transportation. Additionally, the Pacific Ocean plays a role in recreational activities, including surfing and sailing, drawing tourists and locals alike. Its waters also contribute to the unique coastal ecosystem, vital for wildlife and plant life along California's coastline.