Ocean in the bottle

Small kids project we did a while ago.
You will need a bottle, some rocks, small toys or anything you want to be in your "ocean". Water and oil. Food coloring.
We did 2 bottles - one with vegetable oil and one with baby oil.
With vegetable oil bubbles are a little yellow, but moving faster, but also more foamy.
With baby oil it made "ocean" brighter, no foam, but items don't float as much.
If you flip or shake the bottle, you will see how bubbles trying to go to the top almost immediately.