Slb, I think you are right. I had never heard of the PN flying boats, but it looked awfully familiar, which I now put down to having found out that the PN series were a development of the Felixstowe flying boats.
For Asturias:
The transfer of Ryan from helicopter to submarine was filmed in the area of the Juan de Fuca Strait and Puget Sound at Port Angeles, Washington State. The area is supposedly renowned for its mists and rain but, wouldn't you know it?, production was held up by day after day of bright sunshine.