Johnson-Smithsonian Deep-Sea Expedition to the Puerto Rico Trench, 1933.

Mr. Eldridge Johnson approached the Smithsonian Institution offering the use of his yacht Caroline, to be completely outfitted, at his own expense, with the most modern devices for oceanographic work. The Institution detailed Dr. Paul Bartsch to the expedition. Work was concentrated at the rim of the deep because of the short time span of the expedition. Marvelous catches of marine organisms, from vertebrates to protozoa, and aquatic plants were made, many of which were previously unknown to science. Besides biological work, the expedition also carried on meteorological, physical and chemical investigations. The expedition also made soundings, by means of the echo-sounding device given and installed by the Navy Department, to determine depths of the trench. Land collecting was done in Puerto Rico, Mona Island, Santa Domingo and the Virgin Islands. This venture was originally planned to span four years; however, due to the economic depression and the conditions in Europe, Mr. Johnson did not participate in further expeditions. Expedition destination: Puerto Rico Trench