Ishmael finds it necessary to separate fact from fiction in his account, in order that it be made more credible to his reader.

First, Ishmael says that it is common enough that a whale escapes a hunting crew with a harpoon sticking out of its back; so common, in fact, that Ishmael himself knows of a handful of instances in which a whale so struck escapes and is then harpooned by the same harpooner after some time has passed.

Second, there have been many famous whales in the history of whaling. These whales, who often combine ferocity with distinct markings, have names like Timor Jack and Morquan. Some of these have been hunted down by certain captains who have set out for the purpose.

Third, the danger of whaling is only understood vaguely, owing to the remoteness of the work. It is very dangerous, Ishmael says, and implores his readers to be economical when using whale-oil to light their lanterns. Every gallon burned represents a drop of human blood.

Fourth, readers tend to underestimate the size and power of the whale. Ishmael recounts many historical accounts of whales entirely destroying large ships at sea. These stories go back to the Roman period of earliest Christianity.