Blue Whale is the world largest (30m/100ft) and also the second loudest (189 underwater dB) animal, has been reported to communicate for about 1600 miles or 2600 km away. This distance is approximately the distance of Puerto Rico to the shores of Newfoundland [1]. The loudest animal goes to Sperm Whale with 230 underwater dB, and it's louder than the sound of jet engine at take-off. According to experts, whale's consciousness and sense of self is based on sound, not sight.
They communicate using sound types namely repeated songs (each song quantum duration of 15-20 seconds) and D calls (down-swept short pulse) [2].
I think that the longer repeated songs are for communication while the short D calls are for echo-location for determining sea depth, icebergs, islands and troupe of shrimps (their staple foods). The latter is similar to the mechanism being used by bats or blind human [3].
[1]http://news.bbc.co.uk/2/hi/science/nature/4297531.stm
[2]https://dosits.org/galleries/audio-gallery/marine-mammals/ba...