it probably still has the potential to cause damage, going around the harbor. it still has an engine, what kind im not sure, and seeing as the Scapa Flow infiltration was in 1941 it obviously isnt the G5 torpedo or anything special but you would rather be safe than sorry.

if it was me i would drag it out of the water and put it on display. that was a torpedo from one of the most stuccessful submarine attacks ever.