Originally Posted By: Faldage
In the old days the lookout on a whaling ship would look for signs of a pod of whales. When a whale surfaces after a long period of being under water the first thing it does is to release the air in its lungs with an explosive exhalation through its blowhole, the single nostril on the top of its head. This would be visible as a cloud of water vapor. The lookout would announce this to the sailors and officers on the deck below by shouting "Thar' she blows!" "Thar'" is a dialect version of the standard English "there".

One correction here. Having seen humpbacks up close and personal, I know they have two blowholes. Most whales being hunted were/are baleen whales, and they all have two. Toothed whales (killer. dolphin, porpoise etc.) only have one. They were not often hunted by whalers. Many people mistakenly believe that whales spout water, which makes no sense, or that the water seen is what was lying on top of the blowhole, which wouldn't be able to account for the size of the spout. The air in the whale's lungs becomes warm and moist during the dive, which then rapidly condenses into water vapor upon hitting the cool ocean air. Different whales have different spout shapes, too. And it's loud! It sounds like something really, really big gasping for air, which I guess it is. But somehow when you hear it close up for the first time, it's startling. :0)
two blowholes