Development of the deep manned submersible Jiaolong was one of the key projects of the National 863 high-tech program. The program's target was to build a practical product to carry out a set of predefined missions. The 7,000 m sea trial was the last stage of the development process, a final phase that incorporated higher risks. During the preceding periods from August 6 to October 20, 2009, May 31 to July 18, 2010, and July 1 to August 18, 2011, the 1,000, 3,000, and 5,000 m depth class tests were successfully completed. The main purpose of this paper is to introduce the results of the 7,000 m depth class test, which was conducted from June 3 to July 16, 2012. The paper describes the general sea trial procedures, and technological and scientific achievements realized during the tests, main faults experienced in the field, along with corresponding troubleshooting methods and suggestions for future application of the Jiaolong submersible. In addition, several conclusions are drawn from all the experiences gained from these sea trials.