On New Year’s Day 2010, three twenty-somethings armed with laptops and video cameras embarked on a mission to find out what makes people happy in the 206 countries where Coca-Cola was sold at the time (the number has since reached 207).

Tony Martin, a Washington, D.C. native, Kelly Ferris of Brussels and Antonio Santiago from Mexico City kicked off Expedition 206 in Madrid, Spain and concluded their unprecedented journey 364 days later with a finish-line celebration at the World of Coca-Cola in Atlanta.

All told, the traveling trio logged more than 275,000 miles and visited 186 countries (they fell short of their goal due to travel logistics, severe weather conditions and other safety concerns). Making stops in cities big and small, they met everyday people and attended marquee events including the Vancouver Olympic Winter Games in Canada, the FIFA World Cup in South Africa and the Shanghai World Expo in China.

They chatted with a surfer in Barbados who advised them to “follow their passion and live their dreams,” learned to “smile away the stress” from a local artisan in Guyana, and heard why a Saint Lucia native “loves life, not things.” They hiked an ancient fort in Nicaragua, shared tea with university students in Senegal, tasted arepas with Venezuelans and slurped Coca-Cola and coconut ice cream floats in Mexico City.

The epic adventure stretched from the snowy region of Poland to the pyramids of Egypt. The team joined thousands of revelers at Carnival in Rio, took in the view from atop the Eiffel Tower in Paris, absorbed the sights and sounds of New Delhi, and tried sumo wrestling in Japan – all in search of the source of happiness.

“People of all countries and cultures told us family and friends are what make them happy most, and they often mentioned good music, good food and sports,” Ferris said in 2011. “The general rule is that people make people happy. When they mention food or music or sports, they talk about sharing those experiences with other people as the true source of happiness.”

Watch Where Does Happiness Live? – a short documentary film about Expedition 206 – here:

Along the way, the tech- and media-savvy globetrotters chronicled their quest in real time through blogs, Twitter and Facebook updates, photos on Flickr and videos on YouTube. The mashup of content united people around the universal theme of happiness and marked Coke’s largest-ever social media experiment. Expedition 206 racked up more than 650 million media impressions worldwide throughout 2010.

Martin added, “It was a long and sometimes challenging journey, but what truly kept us going were the smiling faces and stories of happiness we encountered every step of the way. We knew it was going to be amazing, but I never anticipated the wealth of friends, memories and unique experiences we would collect.”

Read blogs and check out photos from the Expedition 206 team.

Watch country-by-by country video reports.