Cromwell Lock
{{Use British English|date=September 2013}}
{{Use dmy dates|date=January 2024}}
{{Infobox Waterlock
|lock_name = Cromwell Lock
|image= Cromwell Lock and Weir - geograph.org.uk - 152301.jpg
|caption= Cromwell Weir and Lock
|waterway = River Trent
|county = Nottinghamshire
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| coordinates={{Coord|53.14137 |-0.79248|region:GB_type:landmark|display=inline,title}}
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Cromwell Lock is a large navigation lock on the River Trent in Nottinghamshire, England. The first lock to be built on the site was constructed by the Trent Navigation Company, having been authorised by an Act of Parliament obtained in 1906. Construction began in late 1908, as soon as the Company had raised sufficient capital.The Canals of the East Midlands, (1970), p203, Charles Hadfield, David and Charles, {{ISBN|0-7153-4871-X}} The lock was extended in 1935, when an extra pair of gates were added downstream of the main lock, effectively forming a second lock. The lock was further improved in 1960, when the two locks were made into one, capable of holding eight standard Trent barges.
File:Cromwell Weir - Nottinghamshire (Geograph 2561867 by Jonathan Thacker).jpg
Cromwell Weir by the side of the lock is one of the largest weirs on the Trent and marks the tidal limit of the river.{{cite web|url=http://www.waterscape.com/media/documents/84.pdf| title= River Trent: A Guide for Boaters|publisher=waterscape.com |accessdate=20 April 2013}}
The site is defined by the Ordnance Survey as the nearest tidal location to Coton in the Elms in Derbyshire, which is the furthest point from the sea in Great Britain, located {{convert|72|km|mi}} away.{{cite web|url=http://news.bbc.co.uk/1/hi/england/derbyshire/3090539.stm | title= The farm furthest from the sea|publisher=BBC News |date=23 July 2003 |accessdate=11 May 2013}}
On 28 September 1975, during an eighty-mile, night navigation exercise in extreme weather conditions, ten members of the 131 Parachute Squadron, Royal Engineers were killed after a power failure caused the navigation lights on the weir to go out and their boat went over the crest. A memorial garden with a block of Scottish granite bearing the names of the men who died, lies next to the lock.{{cite web|url=http://www.parachuteregiment-hsf.org/131%20Independent%20Parachute%20Squadron.htm|title=131 Independent Parachute Squadron|publisher=parachuteregiment-hsf.org |accessdate=11 May 2013}}{{cite web|url=http://www.palacebarracksmemorialgarden.co.uk/cromwell-lock-river-trent-28th-september-1975/| title= Cromwell Lock River Trent 28th September 1975
|publisher=Palace Barracks Memorial Garden |accessdate=11 May 2013}}