While aboard submarine No. 748, the North Korean leader conducted a drill and instructed the captain on navigation methods.
According to the state-run Korean Central News Agency, the North Korean leader directed the unit to "round off the combat preparations ... and remarkably bolster up the underwater operation capability of submarines and modernize and fortify bases."
These initiatives, Kim was quoted as saying, are driven by "the motives of the hateful enemies watching for a chance to invade our land and put spurs to combat operations..."
Kim also inspected "various indoor trainings including the drill for launching torpedoes at the underwater comprehensive training room."
He was reportedly accompanied by senior political-military officer Hwang Pyong-So and military operations bureau director Pyon In-Son.
South Korea regarded the photo montage of the submarine Kim visited, printed in the North's Rodong Sinmun newspaper, as an attempt by Pyongyang "to show off its submarine might."
The printed photos showed a rusty, green submarine believed to be an 1,800-ton Romio-class submarine that was manufactured by the Soviets in the 1950s.
South Korean Ministry of Defense spokesperson Kim Min-seok noted that while "It is quite unusual that North Korea revealed even the inside of its submarine... the submarines that our Navy holds are far superior..."