Nyamulagira Volcano, Congo

Erupting volcanoes—such as the Democratic Republic of the Congo's Nyamulagira, pictured earlier this month—can be destructive, frightening, and beautiful. And right now there are at least seven you can see in action now, if you act fast.

When Nyamulagira, Africa's most active volcano, began shooting 65-story fountains of lava weeks ago, officials at Virunga National Park, which contains the 10,032-foot (3,058-meter) peak, struck while the tourism opportunity was hot, setting up guided tours to a tent site within a mile (1.6 kilometers) of the erupting vent.

So far the effort seems to have worked, boosting tourism to Congo—underscoring what a rare thing an accessible, active volcano is.

"There are not many other persistently active volcanoes," said Phil Leat, a volcanologist with the British Antarctic Survey in Cambridge, U.K. "Most erupt for a while, then stop."

—Richard A. Lovett

Stromboli Volcano, Italy

Long known as the Lighthouse of the Mediterranean, this volcano north of Sicily has been in near-continuous eruption for at least a thousand years.

Visible from the safety of cruise ships or by guided hike (safety helmet required) the 3,031-foot (924 meter) volcano pretty much is the island of Stromboli, but that doesn't mean there isn't room for hotels, shops, and villages along its rugged coast.

Stromboli's eruptions are also relatively safe to watch ("relatively" being the operative word in volcano tourism), with blobs of rock arcing up in photogenic curtains of fire, but no major explosions.

In fact, Stromboli's frequent blasts of hot cinders have been so consistent and so well studied that volcanologists apply the term "Strombolian" to similar eruptions anywhere in the world, Leat said.

Kilauea Volcano, Hawaii

Even safer than Stromboli is Kilauea. Unless, that is, you happen to be in the path of its slow-moving lava flows.

Beginning in 1983, this mountain on the southeast side of Hawaii's Big Island has been in continuous eruption—although the lava (video) hasn't come from its 4,300-foot (1,310-meter) summit—long a major visitor destination in Hawai'i Volcanoes National Park.

Rather, the molten rock has been erupting from the vicinity of a small cone known as Pu'u 'O'o, on the mountain's flank, slowly covering more than 38 square miles (100 square kilometers) of land, burying part of a coastal highway and destroying hundreds of homes.

For the most part, though, it's been an extremely sedate process, as the lava flows mostly underground, through a series of lava tubes. Sometimes, however, the mountain produces a bigger show. Blobs of lava can shoot from vents, for example, and lava-tube ceilings can collapse, revealing incandescent flows beneath.

Puyehue-Cordon Caulle, Chile

Pictured on June 16, this 7,336-foot (2,236-meter) peak in central Chile awoke explosively on June 4, spreading ash around the globe and disrupting air travel as far away as Australia and New Zealand.

According to physicists at the National University of Río Negro in neighboring Argentina, its current active period has emitted enough ash to fill 24 million dump trucks.

"The energy necessary to elevate that mass of materials is estimated in around a thousand kilotons, equivalent to the energy released by 70 nuclear bombs," the scientists told the English edition of the Buenos Aires Herald.

Since then, the volcano has settled down, but it continues to emit ash, occasionally disrupting air travel. In good weather, the towering ash plume is visible for many miles, but the crater itself is inaccessible (and too dangerous to visit).

Etna Volcano, Italy

Towering 10,922 feet (3,329 meters) above the Mediterranean Sea, Etna is the tallest volcano in Italy—high enough that at this time of year it's possible to see fire and snow mingling.

But while steam clouds are common around Etna, it can be difficult to time a visit to see a fiery eruption. Although the mountain has erupted 18 times so far in 2011 (most recently on November 15) many of these eruptions were single-day events, with none lasting longer than five days.

Located on the island of Sicily, Etna is an easy side trip from Stromboli, making it possible, if Etna cooperates, to catch two eruptions for the price of one.

Even when it's not producing a fire show, Etna is a major tourist attraction, bustling with bus tours, skiing, and hiking.

Nyiragongo Volcano, Congo

Just as a visit to Stromboli should come with a side trip to Etna, visitors to Congo's Nyamulagira should take in its neighbor, Nyiragongo volcano.

A perfect cone towering 11,384 feet (3,470 meters) above equatorial Africa, Nyiragongo houses a lava lake in its crater, accessible to intrepid (and fit) visitors via a challenging trek (guides and armed guards required).

Treks set off from nearby Goma—a city of 500,000 dangerously close to the volcano. Nyiragongo has unusually liquid lava that can rush down the slope at startling speeds when the lava lake drains.

"The high speeds [at which] the lavas can flow make this a dangerous and unpredictable killer," volcanologist Leat said.

The treks, which include camping, extend through the night, when the lava becomes a pageant of reds and yellows, according to blogger John Tull.

"The sight is mesmerising," Tull wrote on his blog, Kiwi in Kigali. While "gas plumes waft around, obscuring one moment and revealing the next, the lava lake seethes with implied forces that roar and crackle below. ... The thin surface crust is fractured and re-fractured constantly, like the glaze on a crème caramel."

Near Hierro, Canary Islands

Eruptions aren't always on land. This volcano off Spain's subtropical Canary Islands chain, a tourism destination in itself, is erupting beneath the Atlantic Ocean, producing giant bubbles of steam and volcanic gases.

Big blobs of frothy volcanic rock known as pumice, up to three feet (one meter) across, have also been reported floating above the eruption site.

Undersea eruptions are actually quite common, but this is a rare example that can be seen from land, Leat said.

That's because the eruption is occurring in shallow water near the coast of Hierro island.

As of October 29, Spanish ocean scientists using a diving robot had determined that the eruptions had so far built a 330-foot-tall (100-meter-tall) cone, rising from the ocean floor, 820 feet (250 meters) beneath the surface.

If the eruption continues, visitors may be able to witness the birth of a new island—as happened in Iceland in 1963, with the birth of the island Surtsey.