Solo world voyager in rowboat counting the strokes to home

In 2011, Sarah Outen set out on a solo voyage around the world. And she's almost done it -- becoming the youngest ever to row across the Indian and Pacific Oceans. Now she's out in the middle of the Atlantic.

On a bike, in a kayak, and in a rowboat, Sarah Outen has been making her way around the world solo for the last four years, 23,700 miles so far.

Next stop, London and home with just 1,500 miles left to row.

Outen started her trip from London in April 2011 and cycled across Europe to Russia, then went on to Japan to row across the Pacific Ocean. It was there, in 2012, that she encountered a tropical storm.

Woman's around-the-world quest nears end

For three days she tried to ride it out through 50-foot waves.

"That was three utterly frightening days when I didn't know if I was going to be okay," she said.

The Japanese Coast Guard had to rescue her.

It took her six months at home to get back her passion for adventure -- and a new boat.

It helped that during that time she met the love of her life, her girlfriend Lucy.

Sarah Outen is within the final 1,500 miles of her worldwide trip. CBS News

She returned to Japan to complete that Pacific Ocean leg, and one night she picked up her satellite phone and asked Lucy to marry her. "I was about a thousand miles out to sea in the middle of the Pacific. Totally alone," she said.

After cycling across North America through a harsh winter, Sarah has spent the summer rowing across an unaccommodating Atlantic Ocean, facing some daunting conditions.

"The Gulf Stream is not quite the freeway that everyone told me it would be," she said in a call from mid-ocean. A storm took her rudder, sending her for a long time in a big circle. "I felt like a bit of an emotional meltdown after a few days of feeling pretty frustrated by the weather."

There's been some good surprises: French sailors brightened her day with fresh food and flowers.

"Thats' the first time I've seen flowers or greenery for three months," she said.

What's keeping her going? Fiance Lucy at the end of the journey.

"We're planning our wedding," she said. "We're getting married next year and that's really special."

Now with a mere 1,500 miles left, she's counting down the weeks and the strokes to home.