Renewable energy sources from the oceans include offshore wind, wave energy, and underwater currents. Sustainable future economies require renewable energy sources. Recent developments in ocean-based renewable energy systems are outlined and forecasts for the next decade are put forth. Offshore wind energy is the fastest growing sector in renewable energy. Anticipated to reach $6 billion per year in Europe by 2006, upwards of 86 MW of capacity from 88 turbines are in place today. Capacity by 2010 is projected to grow to at least 2000 MW. Governmental support in Europe is fueling the development, in part, because of greenhouse gas emission targets. The first commercial-scale wave power facility was established in Scotland. Several proponents plan prototype demonstrations over the next few years. Growth in this sector is anticipated to reach $100 million per annum by 2010. Projects harnessing tidal currents have shifted toward capturing tidal-driven coastal currents. Conservative estimates of $40 million per annum by 2010 appear realistic. Ocean-based renewable energy development lag land-based systems because of significant capital requirements and difficulty obtaining the necessary financing due to risk and market barriers. The technical capabilities, both in engineering and management, exist in the offshore sector to undertake the size and scope of projects envisioned.