The canal towpath on the Lune Aqueduct has been closed due to a sinkhole, says a charity caring for Britain's waterways.
The Canal & River Trust said engineers were working on repairs while also investigating the cause.
The towpath, which is popular with people walking along the canal over the iconic Grade 1 aqueduct at Lancaster, has been fenced off.
A statement on the Canal and River Trust website said: "The towpath at Lune Aqueduct on the Lancaster Canal remains closed due to a sinkhole that has developed along the towpath.
"Our engineers are continuing to work on a method of repair while also investigating the underlying cause. Due to the presence of electricity cables in the area, a full design solution is required before repair works can proceed.
"A further update will be provided on or before Wednesday, 10 June."
The section of towpath has been fenced off. Photo: Canal and River Trust

Residents posting online said there were "large deep holes" on the towpath of at least a foot deep.
The 202 metres (664 feet) long aqueduct carries the canal 16 metres (53 feet) above the River Lune.
It was designed by John Rennie and constructed by Alexander Stevens in 1797. It consists of five 21 metre (70 foot) semi-circular arches.
The Canal and River Trust is the UK's largest canal charity, caring for a 2,000-mile network of waterways.


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