Ocean thermal energy conversion (OTEC) is an energy generation technology that uses cold deep ocean water (DOW) and warm surface water to produce electricity. Active development of OTEC was started in the 1970s with Hawaii as a major research and development center. In the following several decades, small pilot-scale closed-cycle and open-cycle OTEC plants were successfully designed, constructed, and tested. An open-cycle OTEC plant produces both electricity and freshwater. Besides its low temperature, DOW is also nutrient-rich and free from pathogenic bacteria. DOW-enhanced open ocean mariculture can significantly increase the world fish catch and induce an air to water transfer of greenhouse gas CO2. Therefore, an integrated development of DOW as a natural resource is the center of a “blue revolution” that has the potential to solve four of the most urgent world problems: energy, freshwater, food, and global warming. This paper will review technological development of OTEC and open ocean mariculture, followed by a discussion of the prospect of Mainland-Taiwan research collaboration on the technological development and application of DOW resources.