Steel is a popular material for the construction of cruise ships and submarines. In average, it density is close to $7\mathrm{.}85$ g$/$mL$.$ When compare to the density of water $(1\mathrm{.}00$ g$/$mL$,$ both densities determined at the same temperature$),$ it should be expected that steel does not follow in water. However, cruise ships float in water, suggesting their density is less than that of water, while submarines sink, suggesting their density is greater than that of water. However, the are built using the same material, steel, as the principal building material. Explain, using the concept of density, the observed behavior.