How does object float

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

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.