Teen environmental activist Greta Thunberg set sail for Madrid, Spain, from Hampton, Virginia, on November 13th. She’s making the journey across the frigid Atlantic Ocean with a family of popular YouTube creators. Their voyage can be tracked in real time online.

So happy to say I'll hopefully make it to COP25 in Madrid.

I’ve been offered a ride from Virginia on the 48ft catamaran La Vagabonde. Australians @Sailing_LaVaga ,Elayna Carausu & @_NikkiHenderson from England will take me across the Atlantic.

We sail for Europe tomorrow morning! pic.twitter.com/qJcgREe332 — Greta Thunberg (@GretaThunberg) November 12, 2019

Thunberg became a sensation, thanks to her environmental activism, which sparked a global movement of students walking out of class in coordinated strikes to demand action on climate change. Her fame has come along with invitations to attend international gatherings and demonstrations across the globe, but her commitment to tackling the climate crisis includes a vow to avoid the carbon emissions from flying. She made her way to America by boat from Europe in August so that she could catch the United Nations Climate Summit in New York City. Now, she’ll need to navigate the Atlantic again, this time in wintry conditions.

When she arrived in New York, Thunberg was already thinking about the next leg of her trip. She initially expected to travel to Chile by bus, train, and boat to attend the United Nations’ next climate gathering in December. At that conference, states that signed on to the Paris accord are expected to wrap up a “rulebook” on how to implement the international agreement.

“I’ve traveled half around the world, the wrong way”

But her carefully thought-out travel plans were upended last month, along with thousands of others who expected to make their way to Santiago, Chile, for the conference. Thousands of Chileans have taken to the streets over the past four weeks in what began as demonstrations against subway fare hikes but have since grown into a call for a new constitution that better protects their rights. Amid the unrest, Chilean officials backed out of hosting the climate conference.

“It turns out I’ve traveled half around the world, the wrong way,” Thunberg tweeted after it was announced last week that Spain would be the new host of the climate conference. “Now I need to find a way to cross the Atlantic in November... If anyone could help me find transport I would be so grateful.”

Riley Whitelum and Elayna Carausu answered her call. The Australians have spent the last five years aboard their home, a catamaran named La Vagabonde. They document their adventures with baby “stowaway” Lenny on board on YouTube and have 1.18 million subscribers. The vessel is equipped with solar panels, a wind turbine, and hydro-generators to power their low-carbon journey. With up to a four-week voyage ahead, they’ll be cutting it close to get Thunberg to Madrid to catch the event before it closes on December 13th.