Kim's visit took place on 27 August, in advance of North Korea's Navy Day, the Korean Central News Agency reported.
North Korea has not made a big deal of its Navy Day in recent years. But Kim Jong Un did just visit a navy base earlier in August to watch missile launches from a ship.
North Korean state television showed an extensive video report of Kim visiting what it called the Navy Command of the Korean People's Army, without mentioning where it is.
The video showed Kim's motorcade greeted by hundreds of cheering personnel in white uniforms, and extensive video of Kim and his daughter interacting with senior navy officials.