Editing Plymouth Sound (section)

== Description ==
Its southwest and southeast corners are [[Penlee Point, Rame|Penlee Point]] in [[Cornwall]] and [[Wembury Point]] in [[Devon]], a distance of about 3 [[nautical mile]]s (6&nbsp;km). Its northern limit is [[Plymouth Hoe]] giving a north–south distance of nearly 3 nautical miles (6&nbsp;km).

The Sound has three water entrances. The marine entrance is from the [[English Channel]] to the south, with a deep-water channel to the west of the [[Plymouth Breakwater]]. There are two freshwater inlets: one, from the northwest, is from the [[River Tamar]] via the [[Hamoaze]] and [[HMNB Devonport|Devonport Dockyard]], the largest naval dockyard in western Europe. The other, at northeast, is from the [[River Plym]] disgorging into its narrow [[estuary]], [[Cattewater]] harbour between [[Mount Batten]] and the [[The Citadel, Plymouth, England|Royal Citadel]].

In the centre of the Sound, midway between [[Bovisand]] Bay and [[Cawsand Bay]], is [[Plymouth Breakwater]], which creates a [[harbour]] protecting anchored ships from the frequent south-western storms. The [[breakwater (structure)|breakwater]] is around {{convert|1700|yd}} long, stands in around 11 metres / 36 feet of water and was built by [[John Rennie (engineer)|John Rennie]] and [[Joseph Whidbey]] starting in 1812. The breakwater has a {{convert|23|m|ft|adj=mid|-tall}} [[lighthouse]] on its western end and a {{convert|9|m|ft|adj=mid|-tall}} beacon with a spherical cage on top at the eastern end. It is said that the cage is a lifesaving device designed to keep wrecked sailors from drowning in the huge waves of a storm on the low-lying breakwater.

[[Drake's Island]] is 400 metres long and around 100 metres wide and situated at the north of the Sound. It was fortified to defend Drake's Channel, the only deep-water route to Devonport. The ''Bridge'' is a shallow reef that links Drake's Island and the Cornish mainland. At low water the depth of the Bridge can be less than one metre but at high water it can rise to 5 metres. In [[World War I]] this natural barrier was supplemented by other obstructions to prevent [[submarine]]s and small ships attacking the naval base.