The French Riviera is the Mediterranean coastline of the southeast corner of France. There is no official boundary, but it is usually considered to extend from Toulon, Le Lavandou or Saint-Tropez in the west to Menton at the France–Italy border in the east. The coast is entirely within the Provence-Alpes-Côte d'Azur region of France. The Principality of Monaco is a semi-enclave within the region, surrounded on three sides by France and fronting the Mediterranean. Riviera is an Italian word that corresponds to the ancient Ligurian territory, wedged between the Var and Magra rivers. The Côte d'Azur or French Riviera, is a nickname given by France to the County of Nice after its annexation in 1860, because the rain and the Mistral were stopped by the Alps and the climate was similar to that of the north of Italy, even in winter, with a sky as blue as its sea, the French Riviera. When the Mistral and the Tramontane are blowing, this provokes an upwelling phenomenon between Languedoc and Provence: they push the surface waters out to sea and bring deeper, cooler waters up to the seaside.