description from Olaudah Equiano autobiography describing the middle passage.
At last, when the ship we were in, had got in all her cargo, they made ready with many fearful noises, and we were all put under deck, so that we could not see how they managed the vessel. ...The stench of the hold while we were on the coast was so intolerably loathsome....The closeness of the place, and the heat of the climate, added to the number in the ship, which was so crowded that each had scarcely room to turn himself, almost suffocated us. This produced copious perspirations, so that the air soon became unfit for respiration, from a variety of loathsome smells, and brought on a sickness among the slaves, of which many died -- thus falling victims to the improvident avarice, as I may call it, of their purchasers.
The interesting life of Olaudah Equiano 1789