Doesn't say if CSA or not, but wondered if any naval experts on list would have references for submarine named Explorer built in 1865. Seems likely to me to be CSA since it was "retired to Panama" after the war. Other CSA warships were sold to other nations such as Japan. Wm.
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"Pacific Yachting Magazine"
139-Year-Old Submarine Found In Panama

http://www.pacificyachting.com/article.php?sid=268

Marine archeologist James Delgado--Vancouver’s Indiana Jones of the
deep--has uncovered a spectacular marine archeological find on the shores
of a Panamanian island, the Vancouver Sun reports. First thought to be a
derelict Second World War Japanese sub sent to attack the Panama Canal in
the 1940s, Delgado has located a remnant from the U.S. Civil War--a
submarine 139 years old. The piece of marine history was found sitting in
just a few feet of water, once uncovered by low tide, on the Isla San
Telmo in the Bay of Panama.
The vessel, The Sub Marine Explorer, was built in 1865, and retired to
the pearl beds off the Panamanian coast after the U.S. Civil War, where
it searched for pearls at otherwise unexplorable depths. However, the
ship vanished in 1865, and remained unaccounted for until this find.
Delgado identified the vessel by comparing the wreck to its original
plans, published in a 1902 issue of Scientific American.
The Sub Marine Explorer was not the only 19th century submarine born out
of the U.S. Civil War. The H.L. Hunley, a Confederate creation, stands as
the first submarine to sink an enemy vessel in combat, the USS
Housatonic. However, the victory was short-lived, as the crew of the
Hunley perished when the submarine sunk attempting to return to base.