Graceful, powerful, and awesome in size, whales are breathtaking animals. About 50 humans could fit on a blue whale's tongue. These mammals roam the open seas searching for enough food to sustain their gigantic bodies. Whales have been a source of food and fuel for thousands of years, but we rely upon them so much that their survival has become a concern. Even with strict anti-whaling laws on many waters, some species of whales are in serious danger. While looking at extraordinary color photographs, readers will imagine they hear the majestic song of these cetacean giants as they explore their undersea lives.