This is a floating watertight structure, which can be submerged sufficiently to receive a ship by flooding the pontoon tanks, which form the bottom of the dock.
Yinto edada ngaphezu kwamanzi engangeni-manzi, enokutshoniswa ngokwaneleyo ekufumaneni izikhitshana ezinomphatsi othe tyaba xa inqanawa ikhukuliseka, ethi yenze umphantsi wechweba.