The water level in the docks is about four or five metres higher than the River Severn. A lock is therefore required to enable boats to rise up to the docks from the River Severn.

The following sequence of photos show how a boat on the River Severn enters the Gloucester Docks through the lock.

A boat approaches the lock

The lift bridge rises. The lock gates are already open.	The boat enters the lock.

The swing bridge lowers and the lock gates are closed.	The lock is slowly filled with water

When the water is the same height as the water in the dock....	..... the lock gates are opened

The boat leaves the lock......	..... and enters the docks.

The boat enters the main basin in Gloucester docks

From the Docks, boats can access a 16 mile ship canal to Sharpness Docks and the sea beyond.

Key vocabulary

Dock
A place for vessels to load and unload cargo or to be repaired.

Lock
A part of a canal or river that is closed off by gates. The water level in a lock can be changed. A lock is used to raise and lower the boats that are travelling through it. Often found situated next to a weir.

Sluice
A dam which can be raised or lowered to regulate the flow of water.