The past, present, and future AUV technologies developed by the author, who belonged to the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) as the leader of the autonomous underwater vehicle group, are described in this chapter. The first to be presented is the deep and long-distance cruising AUV Urashima, powered by a fuel cell, with the following specifications: 10-m length; 2.5-m width; 2.4-m height; 10-tons weight; 300-km cruising distance; and 3500-m depth diving at 3-kt speed autonomously in the ocean. It is used for sea bottom surveys in earthquake areas and for research of global warming phenomena. The second AUV technology described is the next-generation AUV designed by the author for higher manoeuvrability and longer distance cruising than Urashima. Third, this chapter details biomanoeuvring AUVs, which are fish-like swimming robots used for various purposes in scientific research. Finally, a marine system network based on AUVs is described.