The first submarine to successfully dive, cruise below the water surface and emerge to the surface again by its own was the Sub Marine Explorer of the German American engineer Julius H. Kroehl (in German, Kröhl), which already comprised many technologies that are still essential to modern submarines.[15] After its public maiden dive in 1866, the Sub Marine Explorer was used for pearl diving off the coast of Panama. Due to its very advanced design, it was capable of diving deeper than 31 meters (103 feet), remarkably deeper than any other submarine built before.[16]