NR-1 Sinkhole interest, as sinkholes are generally believed to form only in environments which are subaerial, or exposed to the air. In contrast, the NR-1 Sinkhole is believed to be too deep underwater for the area to have been exposed to the air during formation in the Neogene. It was the first documented evidence suggesting that it is possible for karst sinkholes to form entirely underwater. NR-1 Sinkhole The NR-1 Sinkhole is a giant underwater sinkhole located in the Straits of Florida southwest of Key West, Florida. It is found at an approximate depth of of water at the foot of the
Danube Sinkhole other hand, to decide the smoldering controversy over the quantitative impact of the Danube sinkhole, which is known as the Danube Sinkhole case (). As the karst is developing, future sinkhole stretches cannot be accurately predicted. The underground river Danube annually removes about 7,000 tons of lime, that is 2,700 cubic meters, from the karst system. Future expansions or collapses in the underground system are conceivable, which would show above ground as sinkholes or ponors. In the long run, today's upper Danube will probably be redirected entirely into the Radolfzeller Aach, and thus to the Rhine. This would mean that