How do you make something that float sink?

How do you make something that float sink?

How do I “force” a naturally boyant object to sink in water?

This might sound rather obvious but one guaranteed method is to attach the bouyant object to another object which is made of a substance that is much denser than water, like a ship’s anchor. This seems to be the easiest solution. More information would be required to give a better answer i.e. How big is the object? Is there somewhere on the object that you could attach a rope to? etc