DSV Shinkai
The Shinkai is a manned research submersible that can dive up to a depth of 600 m. It was completed in 1970, and until 1981 it had the greatest depth range of any manned research vehicle in Japan. The Shinkai is owned and run by the Japan Coast Guard and it is launched from the support vessel Otomemaru.
Two diameter, thick high-strength low-alloy steel pressure hulls connected by a tunnel. Pilots and observers are housed in the forward hull with mechanical and power supplies in aft hull. A escape sphere was mounted on the forward hull. Access was through four hatches with one emergency escape hatch. Five view ports with 90° viewing angle in the forward sphere, three inside diameter for forward viewing and one inside diameter on each side.