*insert awkward splooshing sound here*

Never did learn how to dive. Maybe I should look it up on youtube?

The actual historical Maru-yu had several problems diving. It was an experimental ship (made by the Army, which didn't like working with the Navy much) and on its first few test-runs, it failed to dive. Then, it managed to dive, but couldn't surface afterwards. -_-U

Kiso was apocryphally in port at the time of some of this, (although historians say it was probably actually Ooi...) and her crew commented on what a strange-looking submarine she was. (At least, if you count the whole production line of Maru-yus as just being "Maru-Yu"...) Because of this, Maru-yu and Kiso are typically shown as old buddies in KC comics after Maru-yu "proves herself".

NWSiaCB said:

Then, it managed to dive, but couldn't surface afterwards. -_-U

Usually that is called sinking, or we would call every downed ship "expediently converted underwater vessels".

79248cm/s said:

Usually that is called sinking, or we would call every downed ship "expediently converted underwater vessels".

Maintaining depth above seafloor is generally precluded from sinking, though.