Sept. 21, 2011 -- intro: Rugged clay terrain in Australia, expansive cliffs in Ireland and enormous island caves in Vietnam are among the 28 scenic international destinations in a competition to find the new Seven Wonders of the World.
The New7Wonders of Nature campaign is a global competition to select seven natural landscapes as the new seven wonders of the world. The contest is an attempt to "bring our natural heritage onto the same level of appreciation as that which has been made by humans," according to the competition website.
In a tour that spans the globe, ABC News brings you 10 of the most exotic natural landmarks vying for the title of "wonder of the world."
quicklist: 1media: 14563939title: Angel Falls, Venezuelatext: The tallest waterfall in the world, Angel Falls is located in Canaima National Park in Venezuela. The falls are more than 19 times higher than Niagara Falls in New York.
The first Official New 7 Wonders of the World competition was held in 2007 and drew more than 100 million voters who chose seven winners from hundreds of international entries.
quicklist: 2media: 14564114title: Mud Volcanoes, Azerbaijantext: The Mud Volcanoes refer to formations of "geo-excreted liquids and gasses," according to its 7 Wonders of Nature entry. Of the earth's 700 mud volcanoes, 300 are found in Azerbaijan, where they have been known to occasionally emit flames nearly 50 feet high.
quicklist: 3media: 14563971title: Black Forest, Germany text: The Black Forest has inspired legend and folklore for centuries with its expansive woods bordered by the Rhine Valley in southwestern Germany.
Public voting online and via phone for the competition is now under way. The competition was established in 2006 by Swiss-born nature enthusiast Bernard Weber and features 28 international finalists competing for a position on the updated list of wonders. Voters also invited to chat about their favorite finalists on Twitter and the New7Wonders Twitter account has over 11,000 international followers to date.
quicklist: 4media: 14564039title: Jeita Grotto, Lebanontext: A compound of crystallized caves and rivers, the Jeita Grotto in Lebanon is a geographical marvel with its stalactites, stalagmites and rock formations. Taken all together, the caves are more than five and a half miles long and its official entry states that it is also home to one of the biggest stalactites in the world, hanging at near 27 feet long.
quicklist: 5media: 14563993title: Grand Canyon, USAtext: The Grand Canyon in Arizona is the only destination in the continental United States among the 28 finalists in the New 7 Wonders competition. Carved by the waters of the Colorado River over the course of 6 million years, the canyon is nearly 277 river miles long, 18 miles wide and 1 mile deep.
The New 7 Natural Wonders is based on the Seven Ancient Wonders of the World, whose ancient, man-made landmarks include the pyramids of Egypt, Temple of Artemis, the Colossus of Rhodes and the Lighthouse of Alexandria -- all located in the Mediterranean.
quicklist: 6media: 14564026title: Halong Bay, Vietnamtext: Located in the Quáng Ninh province in north Vietnam, Halong Bay is home to nearly 2,000 islands and inlets along its 75-mile coastline. Among its coves, caves, and beaches are floating villages of fisherman, who count among their catch 200 species of fish and 450 different kinds of shellfish. UNESCO recognized the area in 1994 as a world heritage site due to its cultural value, geoclimatic history and scenic landscape
quicklist: 7media: 14563983title: El Yunque, Puerto Ricotext: El Yunque National Forest, located on the tropical island of Puerto Rico, is only 28,000 acres but is home to thousands of unique plans and smaller wildlife creatures.
Weber has been public about the New 7 Wonders' aim to publicize natural landscapes as a treasured heritage.
"This campaign should contribute to the appreciation -- to the knowledge -- of our environment, and not just the one in our country but worldwide," Weber told The Associated Press in 2007. "If we or our children want to save anything, we should first appreciate it."
quicklist: 8media:14564125title: Uluru, Australiatext: Uluru, also known as Ayers Rock in central Australia, is a sandstone formation whose colors change dramatically with the sun's light throughout the day. Once sacred to Aborigines who lived in the area, Uluru is one of Australia's most recognizable natural landscapes.
quicklist: 9media: 14564049title: Mount Kilimanjaro, Tanzaniatext: Mount Kilimanjaro is one of the highest mountain summits in the world, standing 19,336 feet above sea level. Situated in Tanzania's Kilimanjaro National Park, the mountain ecompasses five distinct separate vegetation zones and three dormant volcanoes.
quicklist: 10media: 14564104title: Maldives Islandstext: The Maldives Islands, an island nation composed of more than 1,000 islands in the Indian Ocean, counts among its national ecological treasures immense coral reefs beneath its waters, which are inhabited by thousands of different fish species.