They're stunning, dynamic and dangerous, plus they can teach you a thing or two about the Earth's history. Volcanoes possess undeniable allure, doubling as living laboratories and tourist attractions.
Volcanologist Rebecca Williams spends every second she can studying and relaxing near the Earth's lifeblood: lava.
"I had a real geeky fascination with volcanoes as a kid," says Williams, who is a member of the science faculty at the University of Hull in Yorkshire, England.
Across the globe, travelers are discovering their inner geek, joining scientists like Williams in exploring the geological formations capable of producing incredible natural beauty and unparalleled destruction. Volcanoes are the earth's natural ventilation system, unpredictably capable of jettisoning steam, ash, molten rock and lava.
Here's a list of volcanoes Williams says should be at the top of your must-visit list. Some of them are active, so be sure to check with visitor centers and local tour guides before heading out to explore.
"If (locals) say it's not safe to go someplace, don't go," she says. "But do go (see volcanoes) because it is the most spectacular thing you will ever see."
Tungurahua, Andes Mountains near Baños, Ecuador
Elevation: 16,475 feet
This active volcano high in the Andes Mountains has experienced periods of intensified activity in the past few years. Williams spent a month in 2005 doing research at the volcano known as "The Black Giant." Tungurahua consists of three edifices formed over 100,000 years.
The volcano overlooks the town of Baños, which Williams says is sometimes hit with volcanic mud flows caused by the mixture of rain and ash. During her research, a mudflow, or lahar, threatened to overflow into El Salado Baths, one of Baños' mineral-rich hot springs.
The town is known as a gateway to the Amazon and for its basilica dedicated to the Virgin of the Holy water. The Nuestra Señora del Agua Santa celebration takes place in October and the town's anniversary is in mid-December.
Pantelleria, Sicily, Italy
Elevation: 2,742 feet
Pantelleria's only eruption in the last 3,000 years was underwater. The volcano shares its name with the island, which is known as the "Black Pearl" of the Mediterranean because of its remoteness, world-class wine and its crop of tasty volcanic soil enriched capers. Pantelleria is Sicily's largest offshore island and lies closer to Africa than Italy.
Williams did research for her Ph.D. here between 2006 and 2010 and says an eruption 50,000 years ago spewed ignimbrite deposits so hot that they instantly melted, forming a still visible black and dark green sheet of obsidian glass, often referred to as Green Tuff, across the island.
Pantelleria is home to Grotta di Sataria, a cave with hot springs where, according to legend, Ulysses was kept for seven years by the nymph Calypso. Quiet coves offer great snorkeling and diving.
Mount Etna, Sicily, Italy
Elevation: 10,922 feet
Located on Sicily's east central coast, recent studies show that Mount Etna's unpredictable activity increased significantly in the last decade. Mount Etna is Europe's highest active volcano, erupting 200 times since 1500 B.C., according to National Geographic. Check the national park website and with local guides for information on volcanic activity and excursions. The area was recently added to UNESCO's list of World Heritage sites.
Williams visited when it was covered in snow during the 2006 ski season. She didn't see lava flow at its active vent, but there were active ash eruptions.
"As a tourist you can get pretty close and it puts on a pretty good show," she says.
Mount Etna overlooks Catania, Sicily's second largest city, where visitors can soak up its history in the central Piazza Duomo and at the ruins of a Roman amphitheater. Check out the foundation of many delicious Sicilian dishes at the fish market.
Kilauea, The Big Island, Hawaii
Elevation: 4,008 feet
Since 1983, Kilauea's lava has destroyed 181 homes, a community center, a visitor center, a church and a drive-in, according to the National Park Service. Williams calls it the "Disneyland of volcanoes" because of the near-constant lava oozing that has created almost 500 acres of new land in the last 30 years.