Please, please, please don't try this at home. In this clip, a Lithuanian brother-sister team, both illusionists, goes for a few breath-holding records—the significant one appears to be thirteen minutes and 42 seconds at the start. To hold your breath for a long time, you need to slow your heartbeat significantly. If your heart's not working as hard, then it's not going to burn up the limited supply of oxygen in your blood as quickly. In the same way, the less you do while holding your breath, the better. Eventually, when things start getting ugly, the heart stops sending as much oxygen to the extremities, and focuses on keeping the vital organs stocked with blood. Obviously this pair is keeping these points in mind: You can see that the twins are completely relaxed, their faces not even moving, throughout most of the video.
And the chains? Sorry, can't make sense of those. In the end, the brother appears to hold his breath for more than 15 minutes, and the sister stays under for just a few minutes less. Apparently the pair inhaled pure oxygen before the start, which disqualifies them from the official free-diving record, but surely someone's got to recognize the feat. Then again, who knows what really went on. They are, after all, illusionists.—Gregory Mone