Throughout Bristol's history the gorge has been an important transport route, carrying the River Avon, major roads and two railways. It is the gateway to Bristol Harbour, and provided protection against storms or attack. The Bristol Channel and Avon estuary have a very high tidal range of , second only to Bay of Fundy in Eastern Canada; and the gorge is relatively narrow and meandering, making it notoriously difficult to navigate. Several vessels have grounded in the gorge including the "SS Demerara" soon after her launch in 1851, the schooner "Gipsy" in 1878, the steam tug "Black Eagle" in 1861 and the "Llandaff City". The phrase "ship shape and Bristol fashion" arises from when the main harbour in Bristol was tidal, the bottom of which was rocky. If ships were not of stout construction then they would simply break up as the tide receded, hence the phrase.