The ocean that borders the West Coast of the United States is the Pacific Ocean. It is the largest and deepest of the Earth's oceans, extending from the Arctic Ocean in the north to the Southern Ocean in the south. The Pacific Ocean influences coastal climates, marine ecosystems, and local economies, particularly through fishing, shipping, and tourism. Major cities like San Francisco, Los Angeles, and Seattle are situated along the West Coast, facilitating trade and cultural exchange. The Pacific also plays a vital role in global weather patterns and ocean currents.