Steam Detectives - Season 1 Episode 17 Go After Submarine X!
Overview: When an experimental submarine shows up in Steam City's rivers, it seems like no one can stop it, and that's just the way that Knight Phantom wants it. He's managed to get his hands on one of the Navy's pride and joys, and they'd just as soon keep it under wraps than allow Narutaki and his detective friends get their hands on the truth.