Archaeologists are preparing to rescue a medieval salt ship that has been buried beneath mud in Cheshire for nearly 700 years.
Nantwich was an important place for the medieval salt trade
The 26ft-long ship was carved out of a single oak tree and experts say it is of national importance.
The vessel, which was discovered during work on a building site, was originally used to store brine as part of a medieval salt works in the centre of Nantwich.
The brine would have then been boiled to extract the salt, which was a highly prized commodity at the time.
Examination of the tree rings will give a true age of the ship but experts are confident about their initial estimate that it dates back to the 1300s.
Just two years ago archaeologists working nearby on a similar housing plot found the site of a 2000-year-old Roman salt works.
The process of preserving medieval timbers is complicated, say experts.
The most famous find - the Mary Rose - is sprayed with water to stop the wood from falling apart.
After 700 years under mud, exposure to oxygen is the biggest threat to the salt ship.
The rescue operation is costing more than £100,000.
The ship needs to be kept wet until it can be lifted out over the next few days.
It will then be freeze dried before eventually going on display in a local museum.