What comes next in this sequence: The Mediterranean, the River Seine, an artificial lake in Forest Park?

At the 1908 Summer Olympics in London, six swimming events were contested.[1] These were the first Olympic Games in which a 100-metre pool had been especially constructed (inside the main stadium's track and field oval). Previous Olympic events were swum in open water (1896: The Mediterranean Sea, 1900: The Seine River, 1904: an artificial lake).