Sima Humboldt
 Sima Humboldt (Sima Major) is an enormous sinkhole located on the summit of the plateau of Sarisariñama tepui in Bolívar State Venezuela. It is unusual for several reasons including its enormous size and depth its location on the top of the only forested tepui having a patch of forest on its base and also due to the weathering process that formed this sinkhole.