Finland has been ranked as the world's happiest country for the eighth successive year, with experts citing access to nature and a strong welfare system as factors.

It came ahead of three other Nordic countries in this year's UN-sponsored World Happiness Report, while Latin America's Costa Rica and Mexico entered the top 10 for the first time.

Both the UK and the US slipped down the list to 23rd and 24th respectively - the lowest-ever position for the latter.

The study also found strangers are about twice as kind as people think. It measured trust in strangers by deliberately losing wallets, seeing how many were returned and comparing that with how many people thought would be handed in.

The rate of wallets returned was almost twice as high as people predicted and the study, which gathered evidence from around the world, found belief in the kindness of others was more closely tied to happiness than previously thought.

John F. Helliwell, an economist at the University of British Columbia and a founding editor of the report, said the wallet experiment data showed "people are much happier living where they think people care about each other".

The 13th annual World Happiness Report, released to mark the UN's International Day of Happiness, ranks the world's happiest countries by asking people to evaluate their lives.

Finland again took top spot with an average score of 7.736 out of 10, with Denmark in second.

Experts said family bonds were a factor in Costa Rica's and Mexico's rise in the rankings.

The study, published by the University of Oxford's Wellbeing Research Centre, asked people to rate their own lives on a scale of 0-10 - zero being the worst possible life and 10 being the best possible life.

Country rankings are based on a three-year average of those scores. The top 10 are:

1. Finland

2. Denmark

3. Iceland

4. Sweden

5. Netherlands

6. Costa Rica

7. Norway

8. Israel

9. Luxembourg

10. Mexico

The 2025 World Happiness Report also found:

• declining happiness and social trust in the US and parts of Europe combined to explain the rise and direction of political polarisation;
• sharing meals with others was strongly linked with wellbeing across the globe;
• household size was closely linked to happiness, with four to five people living together enjoying the highest levels of happiness in Mexico and Europe

Jeffrey D. Sachs, president of the UN Sustainable Development Solutions Network, said the findings reconfirmed "happiness is rooted in trust, kindness and social connection".

"It is up to us as virtuous individuals and citizens to translate this vital truth into positive action, thereby fostering peace, civility, and wellbeing in communities worldwide," he said.

Jan-Emmanuel De Neve, director of Oxford's Wellbeing Research Centre, added: "In this era of social isolation and political polarisation we need to find ways to bring people around the table again - doing so is critical for our individual and collective wellbeing."