There's a whale that has been swimming alone since 1992 because its song doesn't get any response from other whales

It's known as the "52Hz Whale" because of the sound frequency at which it sings. Other whales communicate between 12 and 25Hz. Because of this, no other whales respond to its song. The 52Hz whale does not belong to a pod. 

Some of the explanations for why it sings at that frequency is that it could be a malformed whale, or a hybrid of a blue whale and another species. Scientists say that even though the idea of a whale swimming around alone might be poignant, there is nothing wrong with it. "The fact that this individual has been capable of existing in that harsh environment for at least [all these] years indicates there is nothing wrong at all." said a whale researcher in Seattle.

(Source)