'Environmental activist Greta Thunberg has set sail from the UK, bound for UN climate summits in New York and Chile.
Fans gathered to wave her off on her voyage across the Atlantic.
The 16-year-old made a speech ahead of departing from Plymouth on the Malizia II, a solar-powered racing yacht with underwater turbines.
Greta said she was dedicated "to do everything I can" to tackle climate change which was a "very big problem".
The teenager, who refuses to travel by air because of its environmental impact, said of climate sceptics: "There's always going to be people who don't understand or accept the united science, and I will just ignore them, as I'm only acting and communicating on the science."
— Greta Thunberg (@GretaThunberg Aug 14th, 2019
Read more: Greta Thunberg: Climate change activist sets sail from Plymouth