The sun-powered Solar Impulse 2 completed its historic Atlantic crossing Thursday morning, landing in Seville in southern Spain.

The plane left the John F. Kennedy International Airport Monday on its 15th leg of the round-the-world trip. The journey will end where it started, in Abu Dhabi.

“The Atlantic is the symbolic part of the flight,” Bertrand Piccard, pilot and adventurer, told the Guardian from the cockpit a few hours before landing. “It is symbolic because all the means of transportation have always tried to cross the Atlantic, the first steamboats, the first airplane, the first balloons, the first airships and, today, it is the first solar-powered airplane.”

During the journey, Piccard said he spotted whales breaching the waters of the Atlantic and an iceberg that had floated down south from the Arctic. Reports said that the project had hoped to end the Atlantic leg in Paris similar to Charles Lindbergh’s flight in 1927 that made the first solo crossing. But the forecast this week in Paris was for storms, and so Seville was chosen as the safest option. 

“But the goal is not to change aviation, as Charles Lindbergh did, but to inspire people to use [renewable] technologies and show people they can use these technologies every day to have a better quality of life,” Piccard reportedly said.

Project team member Yves Andre Fasel, who liaises with air traffic control, said that setting off from Seville would be easier than from Paris, BBC reported.

“If we would have arrived in Paris like we wished, it would have been very complicated because we would have had to cross a lot of air traffic controls,” he said. “From Seville, if we go along North Africa, I don't think there will be a lot of difficulties — from traffic. The difficulties will be more to do with military reasons and things like that.”

The Solar Impulse’s round-the-world journey is part of a campaign to build support for clean energy technologies. The plane set out on March 9, 2015, from Abu Dhabi and has traveled across Asia and the Pacific without a drop of fuel.

Andre Borschberg, co-pilot and adventurer, broke the record for the longest uninterrupted journey in aviation history when he piloted the plane's 4,000 mile flight between Nagoya in Japan and Hawaii. The trans-Pacific flight lasted 118 hours.

The plane has the same wing span as that of a Boeing 747 and weighs no heavier than a car. It was flown at a speed of 30 miles per hour but can go double that speed when exposed to full sunlight. The plane runs on solar power during the day, and uses battery-stored power at night. It has more than 17,000 solar cells built into wings.