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.
"It was a humbling experience. I realised how little I knew about the world," he says. That was when he started a blog about his time in India.
Alex did a degree in history and anthropology at the University of California, Santa Barbara. After that, he started doing his own short clips and videos which he posted online on YouTube.
Last year, while both were teaching English in Spain, they decided to live and work together to create their own travel films. These were meant just for friends and family members at first, but some of the videos they made of Spain went viral on YouTube and on their website, Vagabrothers.com, and their audience grew.
Winning, as they have found out, is hard work. As part of the contest requirements, they have to make two videos, write two articles and upload about 20 photos for each destination. These are posted on the competition's webpage (www.mydestination.com/BBB).
They do everything themselves, from writing the script to shooting and editing the video footage. They also have to tweet and answer comments from followers on social media.
On top of that, they have to plan for their next destination and fulfil a to-do list at each place. These are activities suggested by local My Destination representatives, but the brothers also give their input.
With little sleep and a gruelling travelling schedule, it is no wonder that the brothers have got on each other's nerves along the way. "But we make up the next morning because we have to work together. Besides, the creative disputes end up creating an even better product," says Marko.
He keeps in his wallet a note that their grandparents wrote them before they embarked on the trip. It reads: "1. Every week, take a day for complete rest and sleep. 2. Love and protect each other. 3. No fighting."
"Whenever we feel weary, we read this," he says.
The brothers know that for all the lows they have experienced - such as the time Marko fell sick and was bed-bound in Iceland, leaving Alex to film on his own - there have been many more highs.
"The world is a big cultural kaleidoscope. We're capturing some of its colours and creating a global conversation with our videos," says Alex.
The brothers are currently in Bali and Lombok in Indonesia and their next stop is Whitsundays and Melbourne in Australia. New Zealand is their last stop, where they will spend Christmas with their extended family.
When they return to the United States in January, they plan to give some of their prize money to charity and use the rest to produce more videos. "We want to educate, entertain and inspire," says Marko.
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