Mazandaran is one of the richest provinces of Iran as regards natural resources. The Caspian Sea is the world’s largest lake on which five countries are situated: Russia, the Republics of Azerbaijan, Kazakhstan and Turkmenistan, and the Islamic Republic of Iran. The last has 992 km of coastline along this lake, most of it over the north of Mazandaran, More than 15 cities and towns of Mazandaran lie on the coast, the most important of which are Ramsar, Tonekabon, Chaloos, Noor and Babolsar. Indeed, this coast is one of the loveliest seaside resorts anywhere in the world. More than 350 rivers run from the Iranian territory towards and into the Caspian where over 100 species of marine creatures may be found, the most important being the sturgeon, salmon and kilka. The salt content of this vast lake is 12.7%. The temperature of the water of this lake is 24-26°C in summer and 10-12°C in winter which makes it an ideal coast for water sports especially in summer.