A charity collection box on Filey's seafront has been broken into and the contents stolen.
The Charity Mine, an old World War 2 sea mine on Cobble Landing which collects money for the Shipwrecked Mariners' Society, was targeted by thieves some time between Friday, 7 and Monday, 10 September.
A spokesperson for North Yorkshire Police said: "This is a particularly callous theft, particularly given the location of the container and the charity involved."
Enquiries are on-going and police patrols in the area have been increased.
Anyone with any information is urged to contact North Yorkshire Police via 101 quoting Incident Number 12180169425.