The Scotian Shelf is an extension of the Atlantic shelf extends out to sea about 100 kilometres along the 120-kilometre stretch of the east coast of Nova Scotia. The shelf is relatively shallow, with an average depth of around 90 metres. However, areas around the shelf plummet to depths of 4000 metres to the south, and 3000 metres to east, where the shelf meets the Atlantic Ocean floor. Sable Island, located 300 kilometres southeast of Halifax, is surrounded by a number of shallow banks, ranging from 25 to 100 metres in depth. The shallow ocean floors around this island have long been a threat to ships and many have sunk. These wrecks, scattered on the ocean floor surrounding this solitary island, have given the area it’s nickname - ‘the Graveyard of the North Atlantic.’ Troughs and basins separate the shallow banks in this area. A large underwater canyon, called ‘the Gully’, forms a long pit into the shelf that reaches a depth of 1000 metres.