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
Dersios sinkhole Dersios sinkhole The Dersios sinkhole (Greek: Σπηλαιοκαταβόθρα "Ο Δέρσιος" "Spilaiokatavothra "O Dhersios"") is a sinkhole in Arcadia, Greece. The sinkhole, which has a depth of , has been known since antiquity and is located towards the north end of the plateau of Palaiochora at a height of 750 m above sea level on mount Parnon. It is about 45 minutes on unsurfaced road from the nearest town of Tyros in the Kynouria region of Arcadia. The sinkhole was first explored in August 1974 to a depth of by a French team (in collaboration with the Hellenic Speleological Society). Since 2003,