Although the essential oils do not mix in well with the water you can safely add a few drops of the eucalyptus essential oil to your bath water which can help your body and skin.
I add 3 drops of eucalyptus oil to my warm bath water when wanting to relax in the bath water.
I also sometimes add a drop or two of the eucalyptus essential oils to on an organic cotton ball and sniff it throughout the day.
The eucalyptus oil helps keep me more alert and has improved my brain function in my opinion.