The STM 500 is a Turkish mini submarine of the 500-tonne class under construction since 2022. The shallow-water diesel-electric submarine is being built by Turkish defense company STM with completion of the first vessel not expected until 2026.
, the customer for the project had not yet been publicly released.
The STM-500 was announced in 2021 at the 10th Naval Systems Seminar in August 2021 as a lower cost and more cost effective subsurface warfare option.[1] Construction began in 2022. It is expected to require four years to complete construction, and up to six years to fully complete the project.
The STM-500 will displace approximately 500 tonnes, have a crew of 18, and be able to transport a squad of 6 special forces personnel. It is being designed to have an endurance of 30 days and a maximum dive depth of 250 meters.[2]
Weapons include up to eight "modern heavy-weight torpedos or guided missiles, delivered via four torpedo tubes.[2] Torpedoes can be fired simultaneously. The sub will be able to carry and launch underwater drones.[1]