The 16-year-old Swedish climate activist Greta Thunberg neared the port of Lisbon, Portugal, early Tuesday after making a nearly three-week-long journey across the Atlantic Ocean in a catamaran in order to attend a United Nations climate change summit in Madrid.

Thunberg is two days late to the UN Climate Change Conference 2019, which began on Monday and will continue until Dec. 10. She will spend Tuesday in Lisbon before taking on an overnight train to Spain to attend the summit where she is to deliver a speech.

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The 45-foot-long La Vagabonde catamaran carrying Thunberg, British navigator Nikki Henderson and the Australian family who own the vessel, first set sail from Hampton, Va., on November 13. The teenager opted to make the 3,400 miles journey via yacht instead of taking a direct flight to Madrid as an act of protest against fossil fuel emissions that come with air travel.

“Heading into Lisbon!!” Thunberg wrote on Twitter just after sunrise.

She shared an image of city lights in Lisbon before daybreak writing: “Land ahoy!”

On Monday, Thunberg shared a selfie of her travel companions, writing: “Day 20. Our last day on the ocean! We can now almost smell land! We expect to arrive at Doca de Santo Amaro, Lisbon sometime between 8.00-10.00 tomorrow morning.”

The mayor of Lisbon, Fernando Medina, as well as a group of Portuguese youth activists from Fridays for Future Lisbon, were set to greet Thunberg at the dock.

The conference in Madrid — organized by Antonio Guterres, UN secretary-general, and Pedro Sanchez, Spain’s caretaker prime minister – will bring together representatives from about 200 countries who signed the 2015 Paris climate accord, France 24 reported.

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“In one way, lots of things have changed, and lots of things have moved in the right direction,” Thunberg told AFP before setting sail from Virginia. “But also in a sense, we have gone a few more months without real action being taken and without people realizing the emergency we are in.”