Today marks the first-ever International Day of Caves and Karst! Most of a cave’s activity occurs unseen. Over a billion people inhabit karst regions—landscapes where rainwater disappears into the rock and reemerges kilometers away, supplying drinking water. Beneath the surface, caves safeguard ancient climates, extinct species, and some of humanity’s earliest artworks. Much of this world remains unmapped and unprotected, which is exactly why the day exists. 🇵🇹 Swipe to go underground in Portugal’s Algarvensis UNESCO Global Geopark with karst above, caves below, and entire ecosystems in between. #UNESCOGeoparks