The Turgai (or Turgay) Sea or Turgai Strait, also known as the West Siberian Sea, was a large shallow body of salt water (an epicontinental or epeiric sea) of the Mesozoic and Cenozoic Eras. It extended north of the present-day Caspian Sea to the "paleo-Arctic" region, and was in existence from Middle Jurassic to Oligocene times, from approximately 160 to 29 million years ago. The Turgai Sea derives its name from a region of modern-day Kazakhstan, with its Turgai River and Turgai Valley.