The Aegean basin is the largest. It covers 87% of the territory of North Macedonia, which is . Vardar, the largest river in this basin, drains 80% of the territory or . Its valley plays an important part in the economy and the communication system of the country. The Vardar Valley project is considered to be crucial for the strategic development of the country. The river Black Drin forms the Adriatic basin, which covers an area of about , i.e., 13% of the territory. It receives water from Lakes Prespa and Ohrid. The Black Sea basin is the smallest with only . It covers the northern side of Mount Skopska Crna Gora. This is the source of the river Binachka Morava, which joins the Morava, and later, the Danube, which flows into the Black Sea. North Macedonia has around fifty ponds and three natural lakes, Lake Ohrid, Lake Prespa and Lake Dojran. In North Macedonia there are nine spa towns and resorts: Banište, Banja Bansko, Istibanja, Katlanovo, Kežovica, Kosovrasti, Banja Kočani, Kumanovski Banji and Negorci.