Scientists in scuba gear rarely get up close and personal with marine animals, because their noisy breathing scares the creatures away.
But professional freediver Christian Redl, 39, who has plunged to depths of 95m just by holding his breath, has managed to get nose to snout with a grey reef shark, and looked a humpback whale in the eye.
These magical moments have prompted the Austrian to support a number of marine conservation projects around the world, and are what spur him to continue the sport of freediving.
“Freediving is like flying underwater. You are light, and everything is silent,” said Mr Redl, who can hold his breath for seven minutes. “And with freediving, I can go almost 100m underwater. In scuba diving, the maximum is only about 30m.”
He has been diving without breathing equipment for almost 20 years, pushing himself to extremes.
Last month, Mr Redl claimed a world record – his ninth – for being the first person to freedive in the frigid waters of the North Pole. He was accompanied only by polar expedition leader and professional photographer Marcus Fillinger.
Mr Redl plunged 30m under ice cover 1.8m thick, and lasted a minute and four seconds in the relatively warm -2 deg C waters. Above ground, the temperature was -30 deg C, freezing on the spot the tears of joy Mr Redl shed at fulfilling a lifelong dream.