Environmental activist Greta Thunberg set sail from Plymouth today on a carbon neutral yacht to attend UN summits in New York and Chile on tackling global warming.
The 16-year-old departed on Wednesday on her trip across the Atlantic on the high-tech racing yacht after she stopped using planes.
The 60ft Malizia II is a zero-carbon vessel, with solar panels and underwater turbines to generate zero-carbon electricity on board.
The teen told the BBC that travelling by boat sends a signal that "the climate change crisis is a real thing".
Ms Thunberg previously said she spent months trying to work out how she could make her journey without flying.
The Swedish teenager will be joining demonstrations and speaking at the UN Climate Action Summit hosted by secretary-general Antonio Guterres in New York in September.
Her "school strikes" have inspired a global protest movement by young people demanding urgent action on climate change and she has previously addressed the annual UN climate conference in Poland.
Ms Thunberg, who is taking a sabbatical year from school, is also planning to visit Canada and Mexico before travelling to this year's UN climate conference, which is taking place in Santiago, Chile, in December, making her journeys by train and bus.
She told business and political leaders at the World Economic Forum in Davos that they should panic, because "our house is on fire", addressed Extinction Rebellion protesters in London, and met with UK MPs.
Greta Thunberg prepares to set sail
The vessel is captained by Boris Herrmann, and Ms Thunberg will also be accompanied on the two-week journey by a filmmaker, her father Svante and Pierre Casiraghi, the grandson of Monaco's late Prince Rainier III and American actress Grace Kelly.
It was announced on Tuesday that the teen will be honoured at this year's GQ Men Of The Year Awards, receiving the Game Changer Of The Year Award, which has been especially created for her.
The new gong "recognises Thunberg's dedication to raising global awareness of climate change", GQ chiefs confirmed.
The long-running awards ceremony, this year hosted by Michael Sheen, celebrates men and women in style, politics, entertainment and sport.
Ms Thunberg, who will receive the award via a video link, said: "I am very grateful and this award is for everyone in the Fridays For Future movement, everyone whose school is striking for the climate.
"We all deserve this award because together we have accomplished so much. So thank you to everyone who has been school striking as well."