Steam powered submarine?

[sunworksco]

John Holland
By the last decade of the nineteenth century steam propulsion had replaced sail power in the U.S. Navy. In 1896, the Navy insisted that submarine designer John Holland build his first contract submarine named the Plunger, with a steam engine for surface propulsion.
John Holland, an Irish-American school teacher and inventor, objected to steam power in submarines. Nonetheless John Holland built the Plunger with three steam engines to meet the Navy's prescribed surface speed.
The Plunger
During dock trials of the Plunger submarine, the temperature in the fire room reached 1370F with the power plant at 2/3 rated output. Similarly, during Plunger's sea trials a crewmember reported, "When we tried to submerge, it was so hot no one could live in her." Today, the nuclear reactor has eliminated this drawback to a heat source and submarines are driven by steam. But, before the advent of nuclear power, the internal combustion engine was the submarine's first viable source of power.
Regards,
Giovanni