Athlete and adventurer, Sarah Outen is catching her breath in New York City, before she takes on the last leg of her self-powered trek around the globe.

After four years of cycling, kayaking and rowing her way across continents, the British adventurer finally has the end of her trip in sight.

"I'm excited for the end. I'll be sad when it's all over but kind of really happy that it's happened. But still trying to keep focused on the task at hand," she said.

The London2London journey has been physically demanding for Outen. It began on 1 April 2011 when she left Tower Bridge in London and kayaked to France. From there, she cycled 11,000 miles across Europe, and then it was back into the kayak to paddle from Russia to Japan.

In 2012 Outen rowed her boat across the Pacific Ocean headed for Alaska. Twenty eight days in, the journey came to an abrupt halt when the boat was hit by a tropical storm and Outen was rescued by the Japanese Coast Guard.

In September of 2013 she headed back to Japan to pick up where she left off. Outen spent 150 days alone at sea, rowing the North Pacific.

Before reaching Alaska, she was diverted to the Aleutian Islands due to bad weather.

Those diversions on the Pacific, along with being separated from her fiancée Lucy, have been the most trying part of the journey, she explained.

"Both of those events required huge logistical, financial, timely, kind of everything considerations to get the journey going again.

"And that's been really difficult at times, and certainly since meeting Lucy who later became my fiancée, just being separated from her has proven really challenging," she said.

Despite the loneliness, Outen continued the journey. In 2014 she kayaked 1,500 miles from Adak along the Aleutian Islands and Alaska.

From there, she cycled 5,000 miles across Canada and the US.

After spending a few days in New York City, she will get back on the bike and head for Cape Cod. From there she will row back across the Atlantic Ocean.

"The daunting thing for me is certainly facing big conditions, stormy conditions. Particularly if I get caught by tail ends of hurricanes or anything like that.

"Facing those conditions by myself is never fun, it's certainly frightening. And you never know what is going to happen.

"You can be confident in your equipment and your set up but you never quite know what will happen. There is no guarantee that I will make it safely to the other side."