Protefs-class submarine
The Protefs class was a group of submarines built for the Hellenic Navy in the late 1920s. The boats were built to a Loire-Simonot design in France and were larger than the preceding Katsonis class built by a different French company.
Four boats were built, all were named after sea gods from Greek mythology.
| Ship | Builder | Launched | Fate |
| Protefs Πρωτεύς | AC de la Loire | 24 October 1927 | sunk 19 December 1940, rammed by Italian torpedo boat Antares off Valona, Albania |
| Nirefs Νηρεύς | AC de la Loire | December 1927 | Decommissioned 1945 |
| Triton | AC de la Loire | 4 April 1928 | sunk 16 November 1942 by German patrol boat UJ2102 near Euboea |
| Glafkos Γλαύκος | Chantiers Navales Français Blainville | 1928 | Lost 4 April 1942 |
The three boats which survived the fall of Greece in 1941 served under overall Royal Navy control in the Eastern Mediterranean.