Rheinmetall Sea Snake 30 mm
The Rheinmetall Sea Snake 30 mm is a close-in weapon system designed by Rheinmetall Air Defence AG for mounting on ships. It is based on the KCE30 30 mm revolver cannon, and was designed by a request of the German Navy.
Source: Wikipedia — Rheinmetall Sea Snake 30 mm (CC BY-SA 4.0)