Photo taken on Aug. 15, 2018 shows the Vikos Gorge in northwest Greece. Vikos is a deep gorge located 30 kilometers northwest of the city of Ioannina.(Xinhua/Lefteris Partsalis)

Photo taken on Aug. 15, 2018 shows the Vikos Gorge in northwest Greece. Vikos is a deep gorge located 30 kilometers northwest of the city of Ioannina.(Xinhua/Lefteris Partsalis)

Photo taken on Aug. 15, 2018 shows the Vikos Gorge in northwest Greece. Vikos is a deep gorge located 30 kilometers northwest of the city of Ioannina.(Xinhua/Lefteris Partsalis)

Photo taken on Aug. 15, 2018 shows visitors enjoying the natural scenery of Vikos Gorge in northwest Greece. Vikos is a deep gorge located 30 kilometers northwest of the city of Ioannina.(Xinhua/Lefteris Partsalis)

Photo taken on Aug. 15, 2018 shows a visitor enjoying the natural scenery of Vikos Gorge in northwest Greece. Vikos is a deep gorge located 30 kilometers northwest of the city of Ioannina.(Xinhua/Lefteris Partsalis)

Photo taken on Aug. 15, 2018 shows visitors enjoying the natural scenery of Vikos Gorge in northwest Greece. Vikos is a deep gorge located 30 kilometers northwest of the city of Ioannina.(Xinhua/Lefteris Partsalis)

Photo taken on Aug. 15, 2018 shows visitors enjoying the natural scenery of Vikos Gorge in northwest Greece. Vikos is a deep gorge located 30 kilometers northwest of the city of Ioannina.(Xinhua/Lefteris Partsalis)