Coos Bay, the second largest bay on the Oregon coast, encompasses over 12,000 acres, which are divided almost evenly between tidelands and submerged lands. The OIMB pier is located less than a mile from the mouth of the bay, which is protected by jetties to both the north and the south. The bay itself is comprised of eleven tidal inlets, including the South Slough National Estuarine Research Reserve, a significant source of freshwater runoff, less than a mile above the pier. Because of this, personnel collect daily temperatures at high tide in order to minimize the effects of the estuarine environment.