Transport

Conditions of transport were appalling but like almost everything else about slavery, conditioned by greed.

Slavers wanted to transport the maximum number of slaves at the highest profit and maximum survival rate.

In practice this meant unbelievably cramped conditions, extraordinarily harsh discipline, and immediate death to any who showed signs of disease.

The crossing mortality rate was about 10%, (1.2 million). Though this is an appalling human toll, it's pretty "good" considering the circumstances.