How does object float

The object float under only one condition: its density is less than density of liquid. Metal ships can float just because it's mass divided by displaced volume (which in fact equals density) is less than water.

As you may know some objects float others do not, this is because some objects contain air or oxygen. for example an orange with a peel floats because the peal contains oxygen and an orange without a peel sinks because it does not contain air at oxygen