MOUNTAIN VIEW, California - 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.

"Geography is really about the world and understanding it," National Geographic Chief Executive John Fahey said after the championship.

"Even though this looks like just a quiz show kind of thing, it is really about having the basic understanding that you need to address some really big issues that we all face," he added.

He cited challenges such as feeding a surging global population and stopping the devastation of ocean life.

"National Geographic's role is to get people to learn about the planet and to care about it, and Google has really picked up that mission and run with it," Fahey said.

The Internet giant has shown a devotion to environmental causes that includes investing in green energy and working with famed ocean defender Sylvia Earle to let people explore precious undersea worlds virtually at Google Earth.

Agence France-Presse