NR-1 Sinkhole 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 Pourtales Escarpment, an area of Quaternary sediment. It was discovered in October 1994 during a survey conducted by the American submarine NR-1, a U.S. Navy nuclear research submarine, and is named for the submarine. It was first identified via side-scan sonar and near-bottom echo sounder data, prompting a second survey in May 1995 to confirm the finding. Discovery of the NR-1 Sinkhole prompted scientific
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