The Martin M-130 Flying Boat was used by Pan American Airways (PAA) for service world wide. The first one delivered was known as the China Clipper. Many other manufacturers used the "flying boat" as a design to get heavy aircraft airborne when sufficient length runways did not exist.
Hoisted under an aeroplane or helicopter? How complicated. Certainly a submarine is more likely, but they wouldn't able to operate in an extremely choppy sea. No this was a normal boat, not a submarine or flying plane. It wasn't on top of the sea.