helicopter to get to the entrance and reached the depth of 1832 m, Verëvkina cave became the second deepest in the world, after Krubera-Voronja. The achievement brought Perovo-speleo team, represented by Demidov, UIS Prize for 2017 in the category The most significant discovery/exploration. In early August 2017 cavers of Perovo speleo club descended to −2155 m, where they found a siphon and returned. In mid-August Perovo-speleo team, with Czech caver Zdenek Dvořak, mapped 7 km of new horizontal passages, reached an underground river with a flowrate of 500 liters per second and two terminal siphons at the depth of 2204 m. Verëvkina became the deepest cave in the world. In February 2018 a small expedition of 4, led by Demidov, reached 2212 m, final depth of the cave, at the bottom of the Captain Nemo siphon. Several expeditions followed, including a photo trip to the bottom of the cave in September 2018 with the English cave photographer Robbie Shone, during which the team was surprised by a rain storm that flooded the lower level of the cave. Final cave length, 17.5 km, was surveyed in August 2019. Demidov also helped to promote scientific research in the cave, where it is possible to access an extensive net of passages below −2000 m without diving, from temperature and water pressure measurements to search for new fauna species. Verëvkina cave exploration was presented at several international events, found a wide reaching echo, and Demidov's experience was called for during the cave-related events of general interest. Other pursuits In October 2006 Demidov participated in an international expedition to Ghar Parau cave in Iran, in July 2007 he joined the CAVEX team to Sima GESM cave in Sierra de las Nieves mountain range in Spain, in September and October 2007 and in September 2010 he took part in the Sino-Anglo-Russian expedition to deep caves of Tianxing, China. In November 2012 Demidov visited Gran Caverna de Santo Tomás in Viñales, Cuba, in August 2013 caves in Northern Macedonia and in August 2014 he participated in another CAVEX team expedition to Spain, to Sima de las Puertas Illamina (BU56). In January 2017 he attended the International Caving Meeting FinalMenteSpeleo2017 in Italy and in November 2017 he took part in cave rescue training in caves of Chatyr-Dag mountains in Crimea. In June 2018 he joined the exploration of the cave W le Donne in Italy. In 2004 he