After 50 years of optimistic predictions that marine mining will soon take off, it still remains to be seen if and when this will happen. In 2018 the total value of all marine mining, including both offshore mining and the so far non-existing deep-seabed mining, was estimated to be around US$35 billion, less than 1 per cent of land-based mining. This paper focuses on the potential economic effects for LICs and MICs of expanding the extraction of marine deposits. The importance for these countries of creating a tailor-made tax regime to capture the optimum benefits from future marine mining is highlighted. Environmental Problems are also discussed. The current status of marine mining is outlined and the likelihood of progress in the near- and
mid-term future is assessed. It seems likely that offshore mining will be of more immediate interest to LICs and MICs than deep-seabed mining, which is much more challenging. Marine mining is a sub-part of the larger blue Economy. The economic, social, and environmental effects of marine
mining should always be seen alongside other vital parts of the blue economy, notably fishing and
tourism, which generate considerable economic value. The paper outlines the history of deep seabed mining and its close connections in the 1960s and 1970s with the Cold War and the fight for independence by former colonies. The paper summarizes the long road leading up to the United Nations Convention on the Law of the Sea, a unique international agreement to share the resources of the least exploited part of planet Earth for the benefit of humankind.