San Francisco Bay is relatively shallow on average, with a deep channel system near the central basin. The deepest point is about 372 feet (approximately 113 meters) under the Golden Gate Bridge, while most of the bay averages around 12 to 15 feet (about 3.7 to 4.6 meters) in depth. In many areas between Hayward and San Mateo, depths are much shallower, commonly around a foot or two, and the overall bay area includes extensive channels carved through a drowned- valley interface.