In the days of Imperial Germany, with colonial possessions, Marines make sense; there were Marines at Tsingtao, and a battalion's worth was on their way home from China when WW I broke out. They wound up fighting in East Africa for the duration.
The Kregismarine had no real need for Marines, though they did have Naval Security Battalions that performed guard duty and base defense functions at Naval bases. Reforming a Marine Corps may have been one of Raeder's long-term plans, but like so much of the DKM's ideas, it wasn't to be.