A growing world population and socio-economic development are at the root of an ever-increasing energy demand throughout the world. Much of this demand is met by means of fossil fuels, leading to greenhouse gas emissions and climate change – hence the need for increasing the share of renewable energy sources in the global energy mix. Marine energy is a reliable, high-density source of energy with limited environmental impacts. Iran, with its long coastline, growing population, increasing energy demands and extreme air pollution, has a great potential for the development of marine energy. However, this potential has not received sufficient legislative or entrepreneurial attention so far. This review covers renewable energy resources in Iran in general – including solar, hydropower, wind, biomass and geothermal energy – with a focus on marine resources – wave and tidal energy. On the basis of the review, it can be stated that there are many energy hotspots with a high potential for marine energy development in the Caspian Sea, the Persian Gulf and the Gulf of Oman.