Tens of thousands of residents of the island of Bali, Indonesia, are evacuating out of the path of a volatile volcano that threatens to erupt for the first time in 54 years. As Mount Agung belches plumes of ash and steam, Bali’s airport has canceled flights through Tuesday, leaving some 59,000 travelers stranded on an island known more for its white sand beaches and tropical waters.

On Monday, the Indonesian National Disaster Management Authority raised the threat level to 4, the highest possible level. “We ask people in the danger zone to evacuate immediately because there’s a potential for a bigger eruption,” Sutopo Purwo Nugroho, a spokesperson for the disaster agency, told reporters on Monday. The authorities may soon widen the zone of evacuation and increase the estimated number of those affected.

Scientists are watching the volcanic activity in real time both seismically and through live video feed. Ash and steam have been photographed shooting up into the air above the volcano for over a week.

Heather Handley, a volcanologist at Macquarie University in Sydney, Australia, told Science Magazine that “it is very hard to tell at this time whether there will be a bigger eruption.” The extent of the eruption depends on whether gases are trapped in the magma, the molten rock that bubbles up from the earth’s core. Water vapor, carbon dioxide, and sulfur dioxide stuck in magma build up pressure, the magazine explained, increasing the likelihood of an explosion. But a slow release of gases, through vents in the mountain, could mean a curtailed eruption.

Volcanologist Janine Krippner told the BBC, “The magma has been moving up from inside, and it’s breaking rock as it goes along. As the magma moves up, water inside the volcano heats up, steam builds up pressure and it gets to a point where the rock just can’t hold it back any more.” That’s where Bali finds the volcano now.

The last time the mountain erupted, in 1963, 1,000 people died in fast-moving mud and lava flows that continued for a full year. The Indonesian authorities worry those same kinds of mud flows, triggered by rains and carrying volcanic material, could again prove deadly.

Bali is a destination for both luxury travelers and backpackers who come with little or no money. The island’s governor, Made Mangku Pastika, is begging local hotels to offer beds for free. “Yes, I’m asking. This is a disaster. Especially for those who have spent all their money,” he told the Guardian. He said he would extend time stamps on tourist visas for those stuck for the foreseeable future. Some 5 million visitors come to the island each year.

These images give a sense of the potential crisis the island is facing.

100,000 locals have been advised to evacuate from the path of the Mount Agung’s potential lava flows.

5 million tourists visit Bali each year. 59,000 are stranded there now.

Locals and tourists alike are at risk for getting caught in both hot and cold lava flows, as well as mud flows. Here, lava muddies the river Yeh Sah.

Rains are washing volcanic material down Mount Agung into rivers and toward villages.

Flights at Bali’s Gusti Ngurah Rai International Airport were canceled Monday as Mount Agung threatened to erupt. Passengers scrambled to find hotels and book new flights.

Lava is only one part of a volcanic eruption. Plumes of smoke from Mount Agung have reached 1,500 meters above its summit.

Here, Balinese Hindus take part in a ceremony in hope of preventing a volcanic eruption.

A view of Mount Agung's eruption at a Balinese temple.

Plumes of steam, smoke, and ash have filled the Balinese sky since last Tuesday.

Some villages are in the direct path of a potential eruption. Below is the Kubu subdistrict in Karangasem Regency, seen on November 25.

It is estimated an additional 50,000 people may need to move out of the reach of the volcano. Here, a mother puts her child to sleep at Gunung Agung Refugee Post in Bali.