Making bubble rings

	An unsuccessful attempt. You can see what should have become the ring. However, half of the air went into the two big bubbles above, destroying it.	Now it worked :-) Note that a fish is inside the ring while its buddies are watching from outside. They find it at least as interesting as I do!

Dolphins create vortices under water with a quick head or fin movement, and then inject air into them with their blowhole. These so-called air core vortex rings have live times of 10 seconds or more and can travel in all directions. Check out this impressive video.

As a diver you can create something similar, quite a bit like smoke rings (either by smokers, but also by vulcanoes). They are not true vortex rings like those made by dolphins, as we don't create a vortex, and our rings will only travel vertically upwards. The principle is the same: a less dense medium rises in a denser environment, like hot air in cold air, or as in our case, air in water. You need a spot where any kind of current, surge or turbulence is absent. In the ocean you should be at least 5 to 8 meters deep to be undisturbed by surface waves. 20 or 30 meters is even better. Sometimes a place behind a steep wall offers enough protection, but it can also work in an open area. This is what you have to do:

• Lie on your back and possibly hold on to something to stabilise yourself. Deflating the BCD helps.
• Rest there for some 10 to 20 seconds and wait until all turbulence you created is gone. Your buddies should stay away a bit and don't fin too much if close.
• Take a deep breath, and wait a bit until previous air bubbles above you have cleared.
• Then take your regulator out, fill your mouth with air and say something like "bob". Try to get as much air into the short "o" as possible by opening your mouth wide (as much as an "o" would accomodate). But don't exhale too much as this would already rip apart the bubble ring. Your lips and cheeks should not vibrate during the "o" sound. These vibrations transmit into the bubble ring and destabilise it, so that it will either not form at all or disintegrate after a few moments.
• A good bubble ring is immediately recognisable by its undisturbed appearance. It rises significantly more slowlier to the surface than normal bubbles. During the ascent it increases in diameter (half a meter or even more) without getting much thinner (as the air expands due to decreasing water pressure at shallower depths). The usual thickness of the air ring is about 2-3cms, further up they can thin out to 1cm before decaying. Life times can be 10 or even 20 seconds before disintegration begins after a rise of 5 or 10 meters. The deeper you are, the more air you exhale (since it is more pressurised), and the larger the bubble ring can become while rising.
• Don't exhale after a good bubble ring since normal air bubbles rise much faster and would destroy the ring. Swim two meters to the side once you need to breath again while having a ring in the water.

With a little practise you'll manage a nice ring every 10 or 20 times, provided you have found a calm spot without turbulence or current.