Sicily is facing its worst aviation disruption in more than two decades as a prolonged eruption of Mount Etna forces hundreds of flight cancellations, stranding thousands during the peak summer holiday season.

Europe’s tallest and most active volcano has been erupting continuously since August 6, producing lava fountains, fresh flows, and persistent ash emissions. Experts say the activity could continue for weeks or even months.

Volcanic ash has caused the greatest disruption, with shifting winds carrying it toward Catania-Fontanarossa Airport, about 30 km south of Etna. On Tuesday, the airport extended restrictions due to “Etna’s eruptive activity and the simultaneous emission of volcanic ash,” limiting arrivals to ten per hour. In recent days, the cap has fallen as low as five as changing winds repeatedly forced schedule revisions under safety procedures.

Catania is Sicily’s busiest airport and the sixth busiest in Italy. Its operator, Societa Aeroporti Catania (SAC), has called the disruption “the most difficult emergency of the last 20 years.” Between August 6 and 12, 36% of some 1,974 scheduled arrivals were canceled, SAC said, while around 630 incoming flights were diverted. By August 13, nearly 800 flights had been canceled, disrupting travel for tens of thousands of passengers.

Drone footage released by the Ruptly video agency on Tuesday showed Etna lighting up the night sky as jets of glowing lava erupted from its summit and flowed down its slopes.

The ongoing eruption stands out for its duration. Salvo Gambino, director of the Etnean Observatory at Italy’s National Institute of Geophysics and Volcanology (INGV), said similar activity usually lasts only a few hours to half a day.

“In this case we have… days of continuous activity. Similar phenomena were seen in the late 1970s,” Gambino told Euronews.

Several parts of Etna are also active simultaneously, with lava fountains and ash emissions at the Voragine crater and multiple vents feeding flows in the Valle del Bove. A new vent opened on the eastern side on Monday, though INGV said the lava currently poses no threat to populated areas.

Italy’s Civil Protection Department has kept Etna at yellow alert, the second of four levels, since June 26. Despite heightened monitoring and restrictions, particularly at higher altitudes, the eruption has drawn large crowds, causing congestion and prompting some hiking closures. The local rescue service has also urged caution following several callouts.