The Amazon rainforest, 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, Weber said Tuesday.
"This campaign should contribute to the appreciation — to the knowledge — of our environment and not just the one in our country but worldwide," he told The Associated Press. "If we or our children want to save anything, we should first appreciate it."
The finalists also include Azerbaijan's Mud Volcanoes, Lebanon's Jeita Grotto, Ireland's Moher Cliffs and Germany's Black Forest.
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 U.N. Educational, Scientific and Cultural Organization, picked the finalists depending on geographical balance, diversity and the importance to human life.
Weber said he was happy the nominees included places that lie in more than one country, such as the Dead Sea or the Amazon rainforest, which makes people work together across borders.
High voter participation has come from Asian countries, including Indonesia, India, Bangladesh and Vietnam, as well as from Latin America, he said.
"U.S. voters' participation is always quite high," he added.
Africa, where most people vote by mobile phones, has had the biggest increase in votes over the last few weeks, Weber said.
Weber declined to give any specific numbers of votes so far. But the organization plans to release details about voter profiles later. Registration on the Web site aims to prevent people from voting twice.
Around 100 million people voted in the selection of the seven manmade 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 broadcasting rights.