Same water temperature all over the Atlantic?

Dan Kappes

Titanic sank in Mid-Atlantic, Lusitania sank near Ireland, and the Empress of Ireland sank in the St. Lawrence River.

In all three of these disasters, many people died because of hypothermia.

Was the water temperature the same in these three different places? And was it the same temperature both day and night? (Titanic sank in the early morning; Lusitania sank in the late afternoon)