Crews cleaning up the Hudson River have stumbled upon a sunken ship.

During Central Hudson's $27-million cleanup of the river, workers saw a piece of the vessel's mast sticking up out of the water. They have used cranes and excavators to try to raise the wreck, but have been unable to.

Dive teams have been called in to determine what else can be done.

An archaeological firm will study the ship to determine where it came from and when it sank. However, it will not be able to access the ship until it is raised, a process that could take days to months, the firm said.