At 370,000 sq km the Caspian (Darya-ye Khazar) is five times the size of Lake Superior. That makes it by far the world’s largest lake. Or does it? Its littoral states (Iran, Russia, Turkmenistan, Azerbaijan and Kazakhstan) can’t decide if the Caspian’s a lake at all. Perhaps it’s a ‘sea’. That’s more than petty semantics. In international legal terms, each nation deserves its own territorial slice of any ‘sea’ it borders. But with a ‘lake’, resources below must be shared equally among all littoral states. So the exact definition has vast economic implications given the Caspian’s immensely valuable offshore oilfields. The debate continues. The Caspian has many environmental worries. Under-sea mud volcanoes and oil vents add to the murk of industrial effluent flowing in through its tributary rivers, notably the Volga. And at 26.5m below sea level, there’s no outlet from which pollution can escape. Pollution along with climate change are probably to blame for increasingly severe algal bloom, the vast annual growths of surface water-weeds which, in summer 2005, covered an astonishing 20,000 sq km of the Caspian. Scientists are also worried by the appearance of Mnemiopsis Leydiyi (a comb jellyfish) whose explosive 1990’s reproduction in the Black Sea had threatened fish stocks there. All this along with heavy over-fishing is a particular worry for the slow-growing Caspian sturgeon, which produces 95% of the world’s caviar, but is now facing possible extinction. Between 1977 and 1994 Caspian Sea levels rose an astonishing 15cm to 20cm per year. Those beaches that survived are mostly grey and ugly, but local holidaymakers don’t seem to mind too much. When Iranians tell you how wonderful the coast is, they might mean because of all the lovely rain. Rasht incorporates rain drops into the calligraphy of its welcome sign. There are even seaside restaurants named Barun (Rain). For people from the desert plateau, the Caspian coast’s regular downpours must seem exotic. But it is still worth a visit to see the local towns and industries that have lived along it’s coasts for thousands of years.