They have hang-glided in Rio de Janeiro, gate-crashed a nomad yurt party in Kazakhstan and danced with members of the Maasai tribe in Tanzania.
Brothers Alex and Marko Ayling, who grew up in San Diego, California, have been to 18 destinations around the world in the past four months without forking out a cent.
This is part of their reward as winners of the Biggest Baddest Bucket List travel competition.
Organised by global online travel resource My Destination, the inaugural contest offered a free six-month holiday with all expenses paid and spending money of up to US$50,000 (S$62,590).
The brothers beat more than 1,200 applicants, who came from more than 110 countries. Most were individual applicants, although some, such as the Aylings, came in pairs.
They first had to submit a video of either a destination they had been to or a dream location, together with a travel blog-style entry with three photos.
They were among 10 finalists - eight individuals and two pairs - who had to complete challenges during the Winners' Week. These included tasks such as making chocolates and rock climbing.
The adventure began in British Columbia, Canada, in July. When they return home in January, the organisers will pay them an extra US$50,000 in prize money.
The siblings were here recently for a week. Singapore is one of the countries on their list. This is Marko's second time here. He was here for two days in 2009 as part of a holiday in South-east Asia, but said the only "Singaporean" thing he did was eat chilli crab. "I really didn't do Singapore justice," says Marko, 27.
This time, he tried much more, from cooking Peranakan food at Violet Oon's Kitchen in Bukit Timah Road to witnessing a wedding in Little India.
The brothers, both single, say they were bitten by the travel bug from an early age as their mother is a flight attendant and their father is a Kiwi expatriate who works as a management consultant. "We grew up between cultures and were always on the move," says Alex, 25.
Their desire to explore the world grew after they graduated from university.
Marko, who has a degree in economics and politics from the University of California, Los Angeles, worked as a consultant in a microfinancing company for about five months in India after graduation.