— Cliff Pickover (@pickover) February 21, 2016
This is from Mental Floss' gallery of 15 cool science GIFs. I love this one:
When you notice that the air bubbles "fall down," you'll realize these divers are actually walking upside down on the underside of the ice on a frozen lake. This becomes possible when they inflate their gear with air, which increases their buoyancy and makes them go up. A little fine tuning, and they can simulate gravity upside down. They can do that as long as they have air in their bottles, because the water pressure around them is supporting their entire bodies from all sides.