Swedish environmental activist Greta Thunberg has been speaking about her trip across the Atlantic on an environmentally-friendly yacht.
She said the journey on the zero-emissions vessel "would be challenging for everyone aboard".
Thunberg will travel on the Malizia II — a racing boat fitted with solar panels and underwater turbines that generates no carbon emissions — to attend the two United Nations climate conferences in New York and Santiago, Chile.
Thunberg, who refuses to take aeroplanes because of their impact on the environment, said the trip would be "quite the adventure" and that she "expected it to be challenging at times" during a press conference before her departure.
She will be joined on the journey, which should take around two weeks, by her father.
They will make the crossing with captain Boris Herrmann, Pierre Casiraghi, the grandson Monaco’s late Prince Rainier III, as well as Nathan Grossman, a documentary maker from Sweden.
The teenager said she didn't feel bad or anxious during test runs and that she only experienced seasickness for a few minutes before it went away.
Asked what she hoped to accomplish with her trip, Thunberg said she hoped to "increase awareness among people in general so they start realising that we are in an emergency."
Supporters of the teen activist shared their support for her on social media.
"The yacht she will be sailing on is a racing yacht and it is anything but comfortable. And even in a comfortable yacht crossing the Atlantic is no picnic. You go girl! Big cudos for finding an alternative to flying!" wrote one user.
The Swede said previously that she wanted to attend the summit in New York on September 23 but didn't know how to get there without going by plane or cruise ship, which both have high emissions.
"Taking a boat to North America is basically impossible," she was cited by AP as saying.
Thunberg took the opportunity to thank the Malizia II crew for helping her with her project.
According to German nonprofit Atmosfair, roundtrip from London to New York generates on average 986kg of CO2 per passenger. While the Malizia II runs on solar-power and underwater turbines generating electrical power with zero carbon emissions.
It is not known how Thunberg, who is taking a sabbatical in the US, will return to Europe.