M-class submarines
M-class submarines statistics:
| Number completed before 1919 | 2 |
| Number completed after 1919 | 1 |
| Lost in action | 0 |
| Lost accidentally | 2 |
| Prototype date | 1918 |
| Surface tonnage | 1600 |
| Submerged tonnage | 1950 |
| Length | 296 feet |
| Engine | Diesel |
| Horsepower | 2,400 |
| Screws | 2 |
| Surface speed | 15.5 knots |
| Submerged speed | 9.5 knots |
| Torpedo tubes | 18 inches |
| Number of torpedoes tubes | 4 |
| Guns | 1 x 3 inches 1 x 12 pounder |
| Crew | 60 to 70 |
