Halifax Harbour is a large natural harbour on the Atlantic coast of Nova Scotia, Canada, located in the Halifax Regional Municipality. Halifax largely owes its existence to the harbour, being one of the largest and deepest ice-free natural harbours in the world. Before Confederation it was one of the most important commercial ports on the Atlantic seaboard. In 1917, it was the site of the world's largest man-made accidental explosion, when the SSÂ Mont-Blanc blew up in the Halifax Explosion on December 6.
The harbour was formed by a drowned glacial valley which succumbed to sea level rise after glaciation. The Sackville River now empties into the upper end of the harbour in Bedford Basin. The harbour also includes the Northwest Arm and The Narrows, a constricted passage to Bedford Basin.