The Grand Canyon and the Great Barrier Reef are competing with 26 other spectacular natural landmarks in the final phase of the global poll to choose the "New 7 Wonders of Nature," organisers said today.
The Amazon rain forest, the Dead Sea, Mount Kilimanjaro in Africa and Ecuador's Galapagos islands are also among the finalists, according to the organization New 7 Wonders led by Swiss adventurer Bernard Weber.
People can vote by Internet or phone. The winners will be announced in 2011 and share in the glory already enjoyed by the seven man-made wonders chosen two years ago.
Over 1 billion people are expected to join in the voting, said Weber.
"This campaign should contribute to the appreciation - to the knowledge - of our environment," he told The Associated Press. "If we or our children want to save anything, we should first appreciate it."
A panel of experts chose the finalists among the 77 nominees that gained the most votes in an early round of polling. People had suggested 261 landmarks in countries all over the world.
The panel chaired by Federico Mayor, former chief of Unesco, the UN Educational, Scientific and Cultural Organization, picked the finalists depending on geographical balance, diversity and the importance to human life, Weber said.
He said he was happy to see that the nominees include places that lie in more than one country, such as the Dead Sea or the Amazon rain forest, which makes people work together across borders.
"Already from the nomination phase, we see the enthusiasm of big countries," Weber said, adding that particular high numbers of votes have come in from Indonesia.
High voter participation has come from other Asian countries, including India, Bangladesh and Vietnam, as well as from Latin America, he said.
Weber declined to give any numbers of votes so far. But the organisation plans to release detail about voter profiles later, he added. Registration on the Web site aims to prevent people from voting twice.
"US voters' participation is always quite high up," he said.
Africa, where most people vote by mobile phones, has had the biggest increase in votes over the last few weeks, Weber said.
The finalists also include Azerbaijan's Mud Volcanoes, Lebanon's Jeita Grotto, Ireland's Moher Cliffs and Germany's Black Forest.
Around 100 million people voted in the selection of the seven man-made wonders in 2007. The winners were the Colosseum, Italy; the Great Wall of China; the Taj Mahal, India; Petra, Jordan; Christ the Redeemer Statue, Brazil; Machu Picchu, Peru; and the Pyramid at Chichen Itza, Mexico.
Choosing world wonders has been a continuing fascination over the centuries. UNESCO keeps updating its list of World Heritage Sites, which now totals 890 places.
The New 7 Wonders campaign aims to promote cultural diversity by supporting, preserving and restoring monuments and natural sites. It relies on private donations and revenue from selling broadcasting rights.
* Full list of the finalists: www.new7wonders.com/