New Delhi, May 3 -- The nerves calm, the mind clear, a deep breath later, Akshay Thatte immersed face-first in the water. He was competing in the Static Apnea category at the AIDA Malaysia Freediving Pool Games last December. By the time he surfaced, 5 minutes and 16 seconds had elapsed. The effort landed him the national record.

In June, he'll be looking to improve on his mark at the World Apnea Pool Championships in Hungary, alongside two other athletes from India, Archana Thiagarajan, 34, and Vachan Gowda, 33.

"It's the paradox of freediving, trying to stay relaxed when all along you're not breathing," Thatte, 36, says.

Freediving ran informally for decades until the International Association for the Development of Apnea (AIDA) was ...