Identifying wildlife can sometimes be challenging when you can see the entire animal, but that rarely happens when whale-watching, unless you’re lucky enough to witness a breach. Most of the time, you’re probably looking at less than 5% of the whale at a time as it swims below the surface.
One identifying characteristic is the blowhole. Did you know that toothed whales (e.g. sperm whales) have a single blowhole, while baleen whales (e.g., grey whales) have a double?
In the above image, you can clearly see the double blowhole, which helps to identify this as a grey whale.