Hi Harold,
Now you are in historically very interesting areas, Scapa Flow!
It is difficult today to fully understand the importance of this area but it has played a significant role in both WWI and WWII.
Not going to highjack the thread but Google Scapa Flow and you will be amazed.
On the Island South Rolandsay there are some gun shelters that are visible from the ferry. AA guns at Hoy downed a Ju88 in the first air raid against the base in 1939.
Here is an overview of the area were you have Hoy (Há-øy = High Island) and the actual Marin Base Scapa Flow @ Lyness to the west, Mainland in the north (with Kirkwall [Churchwall] and the Highland Park Whiskey distillery) and South Rolandsoy on the easy side.
Sorry Bish - will let go now, Harold - I will PM you some pictures of civil nature if you are interested.
With regards
Svenne