Thieves have stolen money from the cafe and office at Bourne Outdoor Swimming Pool on Thursday night.
The thieves climbed over the barbed wire fences using blankets to prevent being caught in the wire. They then broke into the cafe where they stole money before smashing through to the office at the pool off Coggles Causeway.
The pool is a charitable company run by volunteers and relies on donations to stay open.
Bourne Outdoor Swimming Pool management committee member Paula Biggadike said: “We are annoyed because it is such a beautiful place and we have fought for more than 20 years to keep it open and then we get mindless vandalism like this.
“We have had to make further repairs following the break in. We fight for every penny that we get and we don’t need to be spending our funds on these types of things.
The pool opened late on Friday day after police and crime scene investigators surveyed the scenes.
Police are appealing for anyone who saw anything suspicious in the area on Thursday night to call them on 101 quoting incident 131 of August 16.