More than a thousand ships were lost at sea due to the weather and icebergs.
The latter part of the journey often saw food supplies diminish and conditions would worsen. Many children arrived as orphans, their parents having died on board.
As steam ships replaced the slower sailing ships in the 1850s the journey became cheaper, faster and less dangerous. As a result, passenger numbers increased. This also led to more return migration. Many were attracted to the fact that migration was less permanent by the end of the 19th century.
The biggest danger came from disease on board due to cramped and unsanitary conditions. Cholera, typhus and smallpox often broke out to disastrous effect. Those who were vulnerable - the young, the old and the malnourished - were more susceptible to infection and the impact was often life threatening to them.
Doctors and surgeons were employed on board ships but often they fell sick or they simply did not have the ability to treat all conditions and infections.