People are being asked to keep their distance from a visitor to the town which has been seen basking by the riverside.
A seal, which has migrated up The Wash for the summer, has been seen close to the centre of town - however, Boston Borough Council are asking residents not to disturb the animal.
For the past couple of weeks Boston Borough Council’s CCTV operators have been keeping an eye on the welfare of the seal to be sure no harm comes to it or the local residents.
However, they have witnessed people throwing things at it, and have had to alert the police on several occasions - including a child throwing a shoe at it.
The seal is tagged and experts say they have no concerns about it coming up the river and inland. Seals do this at this time of year to come onto land to moult.
A council spokesman added that the seal was not in distress and was not lost and warned people not to splash the seal with water.
They said this is stressful to the animal that has come out of the water to dry off, warm up and rest - they do not need water reapplying.
Seals are wild animals and can and will bite if they feel threatened. They may also carry diseases that could be passed to people or dogs.
CCTV operators will continue to monitor the seal, and will call the police if it is seen to be abused.