Nordic countries are often said to be some of the happiest in the world — and they may be some of the most sustainable places to visit too. If you're not sure what it means to travel sustainably, the Global Destination Sustainability (GDS) Index may be able to help. Now in its ninth year, it ranks places across the world based on things like destination management and environmental performance. One hundred destinations were included in the 2024 index, with Helsinki in first place. More than 50% of the Finnish capital's electricity is renewable, more than 30% of its buses are electric, and 49% of its waste is recycled. Helsinki has also set a goal of being carbon neutral by 2030, and there are lots of green spaces around the city — almost 10,000 hectares per 100,000 people, according to Condé Nast Traveler. Helsinki has previously ranked well in the GDS index, coming in fourth place in 2023, although this is the first time it's taken the top spot. "Being named the world's most sustainable travel destination is proof of the long-term work that has been done in Helsinki," Helsinki Mayor Juhana Vartiainen said. The other cities in the GDS' top five for 2024 are also in Nordic countries, with Gothenburg in second place. The city, which is in the west of Sweden, ranked first in 2023. Copenhagen, Denmark, ranked third, Norway's Bergen came in fourth, and another Danish city, Arthus, was in fifth place. Most of the top 20 cities were in Europe, too, with the exception of Singapore in seventh place, Sydney, Australia, in 10th place, and Goyang, South Korea, in 16th place.