第 174 集: 神秘船隻頻現，促使 Atom 展開調查，尋找潛藏於日本地下的海底隧道。

174

Strange incidents start occurring, such as an event where a vessel that had disappeared in the Japan Sea turns up in the Pacific Ocean. Dr. Ochanomizu thinks that there could be a submarine canal right beneath Japan. So Atom goes in search of the canal, and encounters subterranean people on the ocean floor. (Source: Tezuka Productions)