<P> The Columbia Bar, also frequently called the Columbia River Bar, is a system of bars and shoals at the mouth of the Columbia River spanning the U.S. states of Oregon and Washington . The bar is about 3 miles (5 km) wide and 6 miles (10 km) long . </P> <P> The bar is where the river's current dissipates into the Pacific Ocean, often as large standing waves . The waves are partially caused by the deposition of sediment as the river slows, as well as mixing with ocean waves . The waves, wind, and current are hazardous for vessels of all sizes . The Columbia current varies from 4 to 7 knots westward, and therefore into the predominantly westerly winds and ocean swells, creating significant surface conditions . Unlike other major rivers, the current is focused "like a fire hose" without the benefit of a river delta . Conditions can change from calm to life - threatening in as little as five minutes due to changes of direction of wind and ocean swell . Since 1792, approximately 2,000 large ships have sunk in and around the Columbia Bar, and because of the danger and the numerous shipwrecks the mouth of the Columbia River acquired a reputation worldwide as the Graveyard of the Pacific . </P>

Where does the columbia river meet the pacific ocean