The city is built on the River Lee which divides into two channels at the western end of the city. The city centre is located on the island created by the channels. At the eastern end of the city centre they converge; and the Lee flows around Lough Mahon to Cork Harbour, one of the world's largest natural harbours.[5][6] The city is a major Irish seaport; there are quays and docks along the banks of the Lee on the city's east side.