Flach was the first submarine designed and built in Chile in 1866.
On 3 May 1866, after several days of successful testing, Karl Flach, his son, and nine other Chilean and German crewmen boarded the submarine for another test run. During the test, the submarine sank for reasons unknown; it is now thought to lie at a depth of about 50 meters within the bay of Valparaiso. The Flach was located two days after the sinking by seamen from the English frigate HMS Leander, and a diver named John Wallace was able to see and draw the wreck, which was buried nose-down in the bay's sediment. According to some contemporary sources, an attempt to raise the submarine failed because of its burial.
on 25 April 2007. However, the finding has not been confirmed, because, as of August 2007, sediment still has to be cleared away from the object.