How do whales communicate across entire ocean basins?

The answer

Whales exploit the SOFAR (Sound Fixing and Ranging) channel, a layer of water at roughly 1,000 meters depth where sound speed reaches a minimum, causing sound waves to refract and become trapped. Blue whale calls can reach up to 188 decibels and travel across entire ocean basins through this channel. Fin whales produce low-frequency pulses around 20 Hz that have been detected thousands of kilometers away, effectively allowing long-distance communication that scientists are still working to fully decode.