The ocean that borders the western coast of the United States is the Pacific Ocean. This vast ocean is the largest and deepest in the world, covering more than 63 million square miles. The Pacific coastline stretches from the Mexican border up to Alaska, featuring stunning natural scenery, major cities like Los Angeles and San Francisco, and a rich marine ecosystem. The Pacific Ocean also plays a crucial role in weather patterns and trade routes, linking the U.S. to various countries across the globe.