MLO has activities at five locations on the Big Island. The primary observing site is located at the 3397 m (11,141 ft) level on Mauna Loa's north slope () about 5 km north of the summit Mokuaweoweo. The Mauna Loa Solar Observatory shares this site. The administration and some data processing are done in the Hilo, Hawaii office. Kulani Mauka is a rain collection site. Cape Kumukahi is a flask sample site located on the easternmost point of Hawaii. At the Hilo airport, weekly balloon-borne instruments are prepared and launched to measure ozone from the surface to usually over 30 km.