The Cato Trough or Chesterfield Trough is an oceanic trough in the Coral Sea of the South Pacific Ocean. It separates the continental crust of Australia and Zealandia to within 25km (16miles) and has a depth of 3600m (11,800feet).[1] The trough is underlain by oceanic crust, having formed as a result of seafloor spreading from about 63 to 50 million years ago.[1] [2]