In April through June of 1914 a joint project by Thanhouser and the Williamson Submarine Company produced some 20,000 feet of underwater footage in the Bahamas. Carl Louis Gregory, an important cinematographer in film history, was the Thanhouser cameraman, using the newly-perfected Williamson Submarine, aka Photosphere, a nine-foot-long underwater tube with a viewing window at one end where the camera operator could work perfectly dry while capturing actual underwater views in their natural settings. George M. Williamson and his brother J. Ernest Williamson, sons of the tube’s inventor Capt. C. Williamson, participated both in front and behind the camera. The first Thanhouser release from this footage was the five-reel THE TERRORS OF THE DEEP; after three or four special screenings in July 1914 it was finally released in September. More material was assembled into THIRTY LEAGUES UNDER THE SEA (also released in September). The shark footage of IN DE TROPISCHE ZEE is either the final reel of THIRTY LEAGUES UNDER THE SEA or additional footage not used in the two Thanhouser releases, here assembled in a special Dutch or European release by a Dutch distributor or exhibitor. This title is not mentioned in the Thanhouser records or in the U.S. trade press.