The highest altitude of the county is 5,200m in Chuka/Igambang’ombe and Maara while the lowest is 600m Eastwards in Tharaka. The main physical feature of the county is the 360 Km2of Mt. Kenya forest distributed between Maara and Chuka/Igambang’ombe constituencies.
The forest serves as a tourist attraction, catchment area for Tana River, a source of fuel wood, fodder and honey for the communities living around it. Major hills found in the county landscape include Kiera, Munuguni and Njuguni in Maara constituency and Kijege and Ntugi in Tharaka constituency. The hilly terrain of the County leads to soil erosion hence environment degradation. The terrain also makes construction and maintenance of road networks costly.
The topography of Chuka/Igambang’ombe and Maara constituencies is greatly influenced by the Mt. Kenya volcanic activity creating ‘V’ shaped valleys within which the main tributaries of River Tana flow originating from Mt. Kenya forest.
The tributaries flowing eastwards are: Thuci, Mara, Nithi, Mutonga, Naka, and Ruguti. Tharaka on the other hand is traversedby several rivers, which originate from both the Mt. Kenya and Nyambene Hills, flowing eastwards as tributaries of Tana River. These include Mutonga, Thingithu, Kathita, Thanantu, Thangatha, Kithinu and Ura rivers which provide water for irrigation in the moderately densely populated locations in parts of Tharaka. The region comprises of low, hilly, stony and sandy marginal lowlands with moderate forest cover.