SMS Cöln — a well‑preserved Cöln‑class light cruiser in Scapa Flow lying on its starboard side with bow to the north, depths ~22–36 m, length 115 m and weight ~5,620 t; popular and relatively straightforward to dive (explore bow, boilers, bridge and stern guns), but it is a protected war memorial—removal of artifacts strictly prohibited; visibility best in May and October.