خلیج شیر (به فرانسوی: golfe du Lion، اسپانیایی: golfo de León، ایتالیایی: Golfo del Leone، لاتین: sinus Leonis) یک خلیج گسترده از سواحل دریای مدیترانه است که سواحل ناحیههای لانگداک روسیون و پروانس در فرانسه را از مرز کاتالونیا تا بندر تولون در غرب در بر میگیرد.
The Gulf of Lion (French: golfe du Lion, Spanish: golfo de León, Italian: Golfo del Leone, Occitan: golf del/dau Leon, Catalan: golf del Lleó, Medieval Latin: sinus Leonis, mare Leonis, Classical Latin: sinus Gallicus) is a wide embayment of the Mediterranean coastline of Languedoc-Roussillon and Provence in France, reaching from the border with Catalonia in the west to Toulon.
The chief port on the gulf is Marseille. Toulon is another important port. The fishing industry in the gulf is based on hake (Merluccius merluccius), being bottom-trawled, long-lined and gill-netted and currently declining from over-fishing.
The continental shelf is exposed here as a wide coastal plain, and the offshore terrain slopes rapidly to the Mediterranean's abyssal plain. Much of the coastline is composed of lagoons and salt marsh.
The current name of the gulf appeared at least during the 13th century (in medieval Latin sinus Leonis, mare Leonis) and could come from comparison with a lion: it would simply suggest that this part of the sea is as dangerous as a lion because it has very violent, surprising winds that threaten boats (sailors and fishermen know these dangers very well). This comparison with a lion is suggested by various converging sources: Deroy and Mulon's dictionary of French place names, Mistral's comprehensive Occitan dictionary, Diderot and D'Alembert's famous French encyclopedia and several texts in Latin since the 13th century.
These sources, especially Deroy and Mulon, Diderot and D'Alembert, reject the hypothesis according to which the name would be related to the city of Lyon, since it is too far from the gulf.
The Gulf of Lion is not a simple passive continental margin; it results from Oligocene-Miocene anti-clockwise rotation of the Corsican-Sardinian Block against the European Craton. This extension rejuvenated a very complex tectonic framework inherited from the Tethyan evolution and the Pyrenean orogeny. The Eocene mountain-building event that built the Pyrenees compressed and thickened the entire crust. Oil geologists predict that there will be considerable oil deposits at the seaward margins of the gulf.
The gulf's bottom topography, the Mistral, extended cold weather, and evaporation combine to create a sinking of surface waters which forms the Levantine Intermediate Water of the Mediterranean Sea.