This clip brings to mind a similar experience in Svaalbard in 2003.
Through a hydrophone in the sea comes a series of long whistles that start high and descend, very gradually – ever so slowly – right down the scale. They sound like a cross between The Clangers and fireworks or artillery, but more gentle and sweet. It is bearded seals. This sound is suspended in a deep, vast, echoing underwater world, where crustaceans rustle and click in the far distance.The sounds made by 'our' seals -- (Arctic) bearded seals rather than (Antarctic) Weddell seals -- were more fluted and song-like.
(Herzog clip via Zooillogix)