Ironclads are not the same thing as submarines. Ironclads do not go underwater completely even though the majority of their body may be underwater.
USA. nuclear powered submarines can go faster than 25 knots (nautical miles per hour) underwater.
Submarines todaee are used for underwater exploration,funn,new life underwater.
Submarines?
Submarines have sonars.
Submarines are built with a special design that allows them to be faster underwater. Submarines can be used during a war as a way to sneak up to enemy lines in the water, but still stay hidden.
They are called submarines
Straight to the bottom of the ocean.
To detect underwater mines and submarines.
Naval submarines do not dive deep enough to go near underwater mountains. This is contrary to what you may have seen in the movies. They use sounding charts to determine the depth of the water in which they are navigating. They avoid such underwater objects. Research submarines use cameras and sonar, as well as charts, to guide them.
Sonar
Just like diesel submarines travel underwater, but for much longer periods as the nuclear engine does not consume the oxygen in the air. The older diesel submarines were limited to running on batteries or using a schnorkel to get air for the engines when underwater, so usually they traveled on the surface like regular ships only submerging to prepare for an attack with torpedoes on passing enemy ships. The nuclear submarines can practically travel underwater forever, until they need to be resupplied with food for the crew.