The longest sightline on Earth (2020) (calgaryvisioncentre.com)
Three of the longest sightlines on earth: Mt. Dankova, Krygystan to Hindu Tagh, China 538km (green), Pic de Finestrelles, Spain to Pic Gaspard, France 443km (red), and Mt. Sanford, USA to Denali, USA 318km (pink).