Slave ships, large cargo ships specially converted for the purpose of transporting slaves, especially newly purchased African slaves to the Americas. As many as 20 million Africans were transported by ship. The transportation of slaves from Africa to America was known as the Middle Passage.-Spirits of the Passage
Between 1450 and 1850, 12 million Africans were shipped across the Atlantic, and 10 or 11 million got there alive. A number equal to 1/3 of those shipped might have died in the initial raiding or march to the coast. The volume of the trade increased from the 16th to the 18th centuries, with 80% of the total coming in the latter century.