Thirteen (13) major rivers exist within the region. These rivers are utilized for irrigation and in-land fishery development. Two big lakes - Mainit in Agusan del Norte and Surigao del Norte and Lumao in Agusan del Sur, and the Agusan Marsh in Agusan del Sur and Maniayao Lake at Maniayao at Mount Maniayao or Mt. Mahucdam in Surigao del Norte cover a total area of 15,937 and 19,196 hectares respectively. These lakes are rich fishing grounds and are potential ecotourism sites. There are also six (6) other minor lakes existing in the region utilized as in-land fishing grounds. The estimated annual run-off of the region�s water is 35.671 million cubic meters (MCM) which originates from 108 major rivers. Five of these rivers which flow down to Agusan del Norte and out to Butuan Bay have a total length of 400 kilometers. Fishery & Aquatic Resources The region has a total fishing shoreline of 600 kms. and a total of 34 coastal cities and municipalities. The major fishing grounds are the Butuan Bay, Bohol Sea and Surigao Strait in Agusan del Norte; the Surigao Strait, Dinagat Sound, Hinatuan Passage and Port of Bohol Sea in Surigao del Norte; and the Carrascal Waters, Laguna Bay, Cortes Waters, Cagwait Bay, Bislig Bay and Hinatuan Bay in Surigao del Sur. Of the four provinces, Surigao del Norte is the main producer of fish in Northern Mindanao. The province has seven (7) marine fishery grounds and has also rich inland fishery resources like fresh water, brackish water, and lakes with a total area of 10,225.65 hectares.