Papa Stour is located at the south western end of St Magnus Bay . It are 34 kilometres ( 21 mi ) of rugged coastline which is indented by numerous small embayments and four larger ' voes ' . Hamna Voe ( Old Norse : ' harbour bay ' ) in the south is the most sheltered anchorage and the surrounding cliffs contain a natural rock arch . Housa Voe to the east ( Old Norse : ' house bay ' ) is less secluded but is the main harbour for the island and the ferry 's embarkation point .