The answer to this question is likely the California gray whale (Eschrichtius robustus). These whales are known for their large size, reaching lengths of up to 50 feet and weighing as much as 40 tons. They are commonly found along the coast of California during their annual migration between their feeding grounds in the Arctic and their breeding grounds in the warm waters of Baja California.
Related Q&A：
What is big and gray and lives in California？-Well, let me think. Hmm... Maybe it could be a California gray whale! They are huge, definitely big, and they are gray in color. These magnificent creatures are known to live in the waters off the coast of California. Or perhaps it's a California condor? They are large birds with gray feathers. Oh, but then again, it could also be some kind of a big gray bear that roams the forests of California. It's kind of hard to say for sure without more clues!
