Deep under the ocean, whales make some incredible sounds. Some whales sing songs that can travel for miles through the water. Scientists have even discovered that whales can learn new sounds from each other, a bit like people learning a new song. One very unusual whale became famous because of the sound it made. Its calls were around 52 hertz, which is much higher than the usual calls of the blue and fin whales scientists were studying. People began calling it the 52-Hertz Whale. Nobody knows for certain what kind of whale made the calls, or why they were different. Scientists have listened for the whale for years. It became one of the great musical mysteries of the ocean.