They had to identify countries and regions of the world by economies, politics, latitudes - even by a type of tortoise.
On Wednesday, the National Geographic world championship between teenagers from Canada, Russia and China's Taiwan region hinged on knowing which island has a population of about 57,000 people, with most settlements on its West coast.
US game show host Alex Trebek, who presided over the "brain Olympics" at Google's campus in the California city of Mountain View, added that little of the large island is fit for farming.
Egor Shustov, Masha Samoletova, and Alexander Bondarchuk knew that the gold medal would go to Russia.
The three 16-year-olds had the answer to that final question - Greenland - and they held a narrow lead.
"We realized we were the champions," Shustov said of the moment as he and his teammates basked in victory.
"Sometimes I made stupid mistakes, but sometimes very difficult questions were easy for me," the Russian team captain said while looking back at the competition.
Rare species of owl, tortoise and porcupine were used as clues for questions, along with video clips, tribal drums and recordings of dying languages.
Cities, waterways, volcanoes, islands and other geographic points had to be deduced from hints, and errors spotted in maps.
Each of the finalists was stumped at one point or another in a play-off said to pack some of the toughest questions heard at the 20-year-old competition.
Questions:
1. What is the name of the host?
2. What was the answer to the final question?
3. How old is the competition?
Answers:
1. Alex Trebek
2. Greenland
3. 20-years
(中国日报网英语点津 Julie 编辑)
About the broadcaster:
Lee Hannon is Chief Editor at China Daily with 15-years experience in print and broadcast journalism. Born in England, Lee has traveled extensively around the world as a journalist including four years as a senior editor in Los Angeles. He now lives in Beijing and is happy to move to China and join the China Daily team.