‘’Trieste’’ consisted of a heavy crew sphere suspended from a hull containing tanks filled with gasoline (petrol) for buoyancy,  ballast hoppers filled with iron shot and floodable water tanks to sink.
The "Trieste" was a ship designed with a large, weighted sphere as its main body, which carried gasoline (petrol) for buoyancy. It also had compartments filled with iron shot for ballast and water tanks that could be flooded to sink the vessel.