He stayed underwater for 29 minutes without breathing and felt "nothing"

An incredible story and a new record. Croatian Vitomir Maricic broke a record by holding his breath for 29 minutes and 3 seconds, his body lifted by a pair of floats used by children to learn to swim, in a portable pool last June. He gave an interview to Marca, discussing this record and explaining how the brain works at this time.
"29 minutes? It's a very short period of time, but good things happen in that time. Like a Guinness World Record. Every minute is worth appreciating. As my grandfather used to say, 'You'll never be younger than you are today,'" he said at first. To achieve the record, he initially consumed pure oxygen, no difference from the rest according to the diver.

On what he felt during this record, the surprising answer is, "nothing." "Pain? No, knowing that in this kind of attempt, which very few people in the world can attempt, you are always at the limit. But it's about knowing how to manage the situation, relaxing and breathing at the right pace. We think the brain is lacking oxygen, but that's not true. The loss of consciousness occurs precisely to protect the brain, and we enter a state of relaxation that ends when we feel the air on our face."
Finally, when asked about the risks of this sport, his response is also quite surprising, with great relaxation. "I think it's a relatively safe sport. There's little room for improvisation. And even if, in an aquatic environment, a mistake can be fatal, it's a sport where everything is extremely safe. In a pool, pressure changes don't pose a problem, but it's much more difficult and stressful from a physical and neurological point of view, because you're always reaching your limits."
L'Internaute