Varna (Bulgaria) IOM representatives T. Abramowski (Director General), K. Mianowicz and J. Jerzy took part in the XVI. International Conference of the Open and Underwater Mining of Minerals, which took place in Varna, Bulgaria on September 6-10, 2021. The aim of participation in the conference was to present the results of research on the deep-sea environment as well as technological and economic aspects of the exploitation of polymetallic nodules. As part of the issue of “Modern technologies and facilities in underwater mining of minerals”, IOM representatives presented papers: (1) Advances on technological and economic factors in the development of the deep-sea polymetallic nodules project of the Interoceanmetal Joint Organization and (2) Application of high-resolution imaging survey for rapid maintaining of biodiversity in the areas impacted by deep-sea nodule mining.