(CNN) Teenage climate activist Greta Thunberg is making landfall in New York after sailing across the Atlantic for the past 15 days.

The 16-year-old tweeted in the early hours of Wednesday morning that she could see the lights of New York City and Long Island.

Land!! The lights of Long Island and New York City ahead. pic.twitter.com/OtDyQOWtF5 — Greta Thunberg (@GretaThunberg) August 28, 2019

She had originally been expected to dock her vessel on Tuesday but was held up in rough seas south of Nova Scotia.

Thunberg has been sailing to New York to speak at the UN Climate Action Summit on September 23, and traveled on a zero-emissions sailboat to reduce the environmental impact of her journey, according to a statement from her team.

She set sail on her vessel, the Malizia II, from Plymouth, UK on August 14, and has been documenting her journey on social media.

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