A cave so large - trees grow within it
Son Doong Cave is located in the heart of the Phong Nha Ke Bang National Park in Quang Binh province of Central Vietnam. Only recently explored in 2009-2010, Son Doong Cave has only been open to the public since 2013.[So...
https://www.neatorama.com/2018/11/29/A-cave-so-large-trees-grow-within-it/