There is a sandbar in Sydney Harbour that forms a boundary to the inner harbour, where the SYSCO wharf is found. Although harbour ice forms in the inner harbour between the end of January and the middle of March, this sandbar helps to protect the inner harbour from drift ice, floating down from the Gulf of St. Lawrence.

The majority of the vessels that come to Sydney Harbour are ice-class vessels and are suited to dealing with harbour ice, although when drift ice does enter the harbour an icebreaker is required. This has occurred two or three times in the last five years and typically requires one day to free the harbour.

Drift ice is cleared with either an ice breaker or the Marine Atlantic passenger ferry which provides service to and from Newfoundland, and is itself an icebreaker. There have been only one or two instances in the past few years when the ferry was delayed by a day as the result of ice in the Harbour. According to the Harbour Master, the harbour has never been dredged and there is no current need to do so in the future.