What conditions of the ship caused many of the slaves to die?

Equiano describes the sensation of being put under the decks: "I received such a salutation in my nostrils as I had never experienced in my life; so that with the loathsomeness of the stench, and crying together, I became so sick and low that I was not able to eat, nor had I the least desire to taste anything." He felt a little better when he found people of his own nation, but was convinced that the white men were evil spirits. Similarly, he was amazed by the workings of the ship, and thought it moved by magic.

Down in the hold, he was assaulted by hot air unfit to breathe because of its loathsome smells. Many people grew sick and died, "thus falling victims to the improvident avarice, as I may call it, of their purchasers." The screams and cries of anguish and terror made the hold like a scene from Hell. Thankfully, because of Equiano's young age, he was not put into chains and had more freedom to move about.

The white men were strange to him, especially in their wastefulness. One day, they captured a large fish and only took a small part from it, tossing it back into the sea despite the cries of hungry slaves. They were also remarkably cruel. When three slaves tried to jump overboard and end their lives, one of them was recaptured and flogged mercilessly. Likewise, the slaves down below were cruelly denied any fresh air.