A BLUE WORLD: Just-released drone video captured a blue whale calf swimming under and around a whale-watcher's boat near San Diego, California, Tuesday. https://abcn.ws/2FLyzTu | ABC World News Tonight with David Muir

This is the moment a CNN crew filmed a blue whale swimming directly under their boat. As part of Rolex's Perpetual Planet initiative, the conservationists on board are on a mission to advocate for ocean protection. cnn.com/calltoearth #CallToEarth #PerpetualPlanet | CNN

Blue whale vocalizations are very low frequency sounds with some in the 15 Hz range. These tones characteristically travel long distances due to the high power, but also due to very long-wavelengths (over 300 feet for 15 Hz). This enables their songs to be heard thousands of miles from the source. We can assume that the projection distance is important (Nature can be extravagant, but she is never wasteful), but we can only speculate why they need to broadcast their songs across ocean basins. The