This allows them to dive up to 3,000 meters deep and stay underwater for up to two hours. The sperm whale sets several records. It is the largest toothed whale and has the biggest mouth of all whales. It could even swallow a human whole. However, it is not dangerous to humans, as it only targets squid. It consumes about 1.5 tons of them each day. Its brain weighs 9.5 kilograms, making it the heaviest of all mammals. With the help of echolocation, it navigates through the oceans. Underwater, it can be heard whistling, squeaking, and groaning over several kilometers.