The Koryu-class midget submarine of the Imperial Japanese Navy. The subs were 26.25 meters long and had a displacement of 59.3 tons.
https://s3-us-west-1.amazonaws.com/h..._submarine.jpg
Previously:
https://www.homemadetools.net/forum/...539#post162559
https://www.homemadetools.net/forum/...344#post161720
https://www.homemadetools.net/forum/...220#post161319
https://www.homemadetools.net/forum/...984#post160478
https://www.homemadetools.net/forum/...762#post159745
https://www.homemadetools.net/forum/...140#post157564