water inlets on ship

Not really an aviation topic, but at least naval.

Was looking at a book on the Iowa class battleships. Went through the
engineering section and saw the design of the engines. A thought came
to mind - where does the cooling water come from or are they single pass
engines with the steam exhausted overboard. That sounds grossly
inefficient and makes more sense to have a closed loop design with
cooling water.

Is there a set of scoops below the waterline or some type of flush
opening below the waterline to draw in seawater for cooling? Or is it
all "fresh" water that has been drawn through the evaporators.

Is the system similar on any ship? (There, finally a tie into aviation
if a carrier uses a similar powerplant)

Thanks in advance

MAH