John Krasinski once risked his own life to save a woman from drowning.

The 38-year-old actor has revealed that during his travels as a teenager he found himself caught in a riptide whilst swimming in the sea, and although the current was dangerous, he risked drowning in order to save a woman who had also been swept up by the waves.

He recalled: ''One of the places I went was this amazing beach called Manuel Antonio that I didn't realise had an insane riptide. While I was swimming there - this is a story I've never told anybody - this Costa Rican girl and an American guy were swimming right next to me, and we were knee-deep.

''I went underwater for a second, and when I came back up he was screaming at the top of his lungs. Literally in three seconds the girl had been swept 150 yards out.

''In that moment, I didn't ask anyone. There was no one to help me. I just went out and tried to save her. And then of course when I got out there, I was in a crosscurrent with her.''

The 'Office' star - who has four-year-old Hazel and 20-month-old Violet with his wife Emily Blunt - insists his decision to help the stranded woman was a ''survival instinct'', and he was surprised when she asked him to ''let her die''.

John - who eventually saved the woman - added to Playboy magazine: ''It was one of those moments of 'Oh my God, you just made a poor choice and it might cost you your life.' But I didn't think about it like that. It was just this survival instinct.

''It was really weird - like the girl was asking me to let her die. But I got her back. When I got within 20 yards or so of the shore, some surfers came out.

''Granted, not everybody needs to have life-or-death experiences, but that changed my entire life. All of a sudden I grew up.''