This seems like a contradiction, but it isn't. Sound attenuation in sea water is extremely dependent on frequency. It is roughly a power law. Very low frequenci

This seems like a contradiction, but it isn't. Sound attenuation in sea water is extremely dependent on frequency. It is roughly a power law. Very low frequencies can easily travel extreme distances (0.001dB/km for 0.1Hz or so), but higher frequencies are attenuated more drastically. Whale song and man made noises have much higher frequencies. A quick Google search claims whale songs are around 80Hz to 4kHz. Absorption is around the 10 to 100dB/km range for 100Hz to 1kHz. So both statements in the article are true.