Mount Lolmalasin is the highest crater mountain in the Ngorongoro Conservation Area and the third tallest mountain in Tanzania and the second highest peak in Arusha region after Mount Kilimanjaro and Mount Meru, reaching about 3,700 meters (12,080 ft) above sea level. 

The mountain lies near the Olmoti Crater on route to Empakaai Crater on the Ngorongoro Conservation Area's eastern border and is located entirely within Nainokanoka ward. The volcano is located in the geographic area known as in the Crater Highlands and is an extinct volcano that last erupted in the pleistocene.  The mountain also is the source of Simiyu River, which flows west to Lake Victoria in Simiyu Region.