This report is destined for both readers with a previous specialised knowledge and those trying to gain insight into a new and rapidly evolving topic. Along with information on what the deep web is, how it operates, the role of ‘The Onion Router’ in the anonymous sale and purchase of illegal drugs, the role of encryption and cryptocurrencies, the content raises certain questions. For example, how will illicit drugs be marketed and trafficked in the future? Are the current tools and responses fit for purpose? How can the EMCDDA address the challenges of monitoring such a dynamic and fast-changing environment?