Canal locks and lifts appear all along waterways, helping boats to climb hills. They come in many varieties but our handy guide can help you tell them apart.
The introduction of locks in the 10th century made it possible for boats to climb the highest hills and mountains. In England and Wales our waterways are now home to many different types of lock. Next time you're out and about see how many different types you can spot.
Pound locks
Pound locks came to Europe in the 14th century and these are the locks that you'll see up and down our canal and river network.
Single locks
Single locks consist of one lock gate and are the most straightforward to use. Not only is it the quickest and simplest way to move the boat from one height to another but it's also the most economical use of water.
Broad locks
Double the width of a single or narrow lock, these allow two narrowboats to go through together, or one wide boat on its own.
Double locks
To increase speed and avoid delays, lock flights were often doubled by building them side by side. This type of lock saves water as more than one boat can go through at any one time.
Originally used as a way to control the flow between different canal company's water, the stop lock worked to completely break the flow of water and was a way to prevent one canal taking large amounts of water from another canal.
The majority of all canals are managed by ourselves now, and people can freely travel from one canal to another. Most stop locks such as Worcester Bar (pictured) have been removed.
Guillotine locks
Mimicking the blade of a guillotine, this lock gate is raised and lowered letting those on the canal through, (safely of course). The vertical gates of a guillotine lock take up less space as it is short and doesn't need to swing open and shut. They are not very common on our waterways, with only a handful of them left - you would find more on rivers.
Significant restoration was carried out on the King's Norton Guillotine lock in 2012. It's now designated as a scheduled ancient monument, which gives it the same statutory protection as Stonehenge.
Staircase locks and flights
Probably one of the most impressive engineering feats on the canal. Created for steep gradients, staircase locks comprise of numerous locks in a row and appear like stairs in the landscape. Staircases don't have pounds in between each gate; the top gate of one lock will also be the bottom gate of lock above.
Flights, however, will normally contain pounds of water in between each gate. Flights can also contain staircases - Foxton Locks, for example, consists of two adjacent five-chamber staircases.
The picture here shows the Caen Hill Flight on the Kennet & Avon Canal, which spans 16 locks. Often when the angle of the hill is so steep, side ponds are used to replenish the water in each lock after use.
