It was apparently considered out of the question to dive by filling the ballast tanks. Perhaps they wouldn't sufficiently increase the Nautilus's specific gravity. Moreover, in order to come back up, it would be necessary to expel the excess water, and our pumps might not have been strong enough to overcome the outside pressure.
Se comprende que no se tratara de sumergirse llenando los depósitos, pues aparte de que no habrían bastado para aumentar suficientemente el peso específico del Nautilus, al remontarse a la superficie habría que expulsar la sobrecarga de agua y las bombas no tendrían la potencia necesaria para vencer la presión exterior.