A former World War II mine used to collect donations for the RNLI has been prised open and plundered.
The charity said the mine on Poole Quay would have contained hundreds of coins.
A volunteer lifeboat crew noticed the lock on the container was damaged on Saturday and a heavy duty replacement was ordered.
But the charity believes a thief returned with tools on Sunday before breaking the lock and stealing the cash.
Volunteer coxswain Jonathan Clark said: "I'm sickened that someone can do this.
"We rely totally on the support of the public as we do not receive any financial assistance from the government. Every little bit helps and counts especially in the current economic climate."
He added: "People passing the station or watching the lifeboats launch often drop loose change into the mine, and every penny donated goes to funding our station."