Onion routing networks, also known as darknets, are private networks that enable anonymous communication over the Internet. They are used by individuals and organizations to protect their privacy, but they also attract cybercriminals who exploit the anonymity provided by these networks for illegal activities. This paper comprehensively analyzes cybercrime threats and countermeasures in onion routing networks. We review the various types of cybercrime that occur in these networks, including drug trafficking, fraud, hacking, and other illicit activities. We then discuss the challenges associated with detecting and mitigating cybercrime in onion routing networks, such as the difficulty of tracing illegal activities back to their source due to the strong anonymity guarantees provided by these networks. We also explore the countermeasures that have been proposed and implemented to combat cybercrime in onion routing networks, including law enforcement efforts, technological solutions, and policy interventions. Finally, we highlight the limitations of existing countermeasures and identify potential directions for future research in this area, including the need for interdisciplinary approaches that combine technical, legal, and social perspectives to effectively combat cybercrime in onion routing networks.