Contractor, Knights Brown was working on the 1.2km stretch of improved sea defences between Knab Rock and Oystermouth Square when the digger became stranded after breaking down.
The contractor has said that there were no injuries in the incident and that it is working to contain any potential pollution the submerging of the equipment has caused.

(Image: Siobhan Nolan-farmer / Facebook)
A spokesperson for Knights Brown contractors who are working on the sea defence project for Swansea Council said: “On Thursday, 18 May 2023, an excavator operating on Mumbles Beach as part of the coastal defences contract being undertaken by Knights Brown for Swansea Council, became stranded following a mechanical failure.
“The operator exited the machine safely and we can confirm that nobody has been injured.
“It is our standard practice that machines operating in ecologically sensitive areas use biodegradable oil and as a result, the risk of environmental damage is negligible. We have, however, taken the additional precaution of deploying spill booms as a containment measure.
“A recovery plan has been drawn up with the assistance of specialist contractors. Temporary access tracks will be installed on the beach and recovery vehicles will retrieve the machine at low tide in the coming days.
“As a matter of public safety, we ask that people adhere to the safety measures that have been put in place and not attempt to access the beach to get close to the machine.”
The work at Mumbles is aimed at improving flood and coastal erosion protection to around 130 properties.
It will also see improvements to the promenade including a wider shared pedestrian and cycle pathway, landscaping and new play areas.
(Lead image: Mike Valentine / Facebook)