1. THE COMBINATION OF A DRY DOCK DISPOSED IN THE GROUND ADJACENT A BODY OF WATER AND COMPRISING AN ENCLOSURE HAVING A BOTTOM, A PERIPHERAL SHELL AND A TRANSVERSE HORIZONTAL PARTITION SPACED ABOVE SAID BOTTOM, SAID PARTITION SEPARATING SAID ENCLOSURE INTO AN UPPER DRY DOCK CHAMBER HAVING SAID PARTITION AS THE FLOOR THEREOF AND A LOWER DRAIN CHAMBER HAVING SAID PARTITION AS THE CEILING THEREOF, GATE MEANS PROVIDED IN SAID PERIPHERAL SHELL AND WHEN OPEN COMMUNICATING THE STATED BODY OF WATER, SAID DRY DOCK CHAMBER ONLY WHEREBY THE LATTER MAY BE FILLED WITH WATER TO THE LEVEL OF THE STATED BODY OF WATER, SAID DRAIN CHAMBER HAVING A CAPACITY GREATER THAN SAID DRY DOCK CHAMBER, VALVED CONDUIT MEANS CONNECTING SAID DRY DOCK CHAMBER TO SAID DRAIN CHAMBER WHEREBY WHEN SAID