The Middle Passage was that portion of the triangular trade
route that brought slaves to the Americas between the 15th and 19th century. It usually lasted somewhere between 30 and 90 days.
Ships would set off loaded with cargo from Europe to Africa and upon arrival, exchange the cargo for slaves. Once loaded with slaves, the ships would embark to the New World and trade the slaves for goods. The goods were then transported back to Europe and the journey would begin again.
In preparation for the journey, all men, women and children who were being held in slave dungeons in Africa had their heads shaved. This was done supposedly to reduce the spread of disease. If the slaves had already been claimed by an "owner", they were branded with hot irons. They were stripped naked, chained in pairs by the ankles, and taken by canoes to the slaving ships which were anchored in the harbors.
Here's a first hand account of one Olaudah Equiano in which he describes how he felt when first encountered the slave ship:
"The first object which saluted my eyes when I arrived on the coast was the sea, and a slave ship which was riding at anchor and waiting for its cargo. These filled me with astonishment, which was soon into terror when I was carried on board. I was immediately handled and tossed up to see if I were sound by some of the crew, and I was now persuaded that I had gotten into a world of bad spirits and that they were going to kill me. Their complexions too differing so much from ours, their hair and the language they spoke (which was very different from any I had ever heard) united to confirm me in this belief. Indeed such were the horrors of my views and fears at the moment that, if ten thousand worlds had been my own, I would have freely parted with them all to have exchanged my condition with that of the meanest slave in my own country. When I looked around the ship too and saw a large furnace of copper boiling, and a multitude of black people of every description chained together, every one of their countenances expressing dejection and sorrow, I know longer doubted my fate, and quite overpowered with horror and anguish, I fell motionless on the deck and fainted...I asked if we were not to be eaten by those white men with horrible looks, red faces and long hair?"