For 25 years, Franklin Roosevelt tried to build the world’s first tidal-electric power plant—by harnessing the Bay of Fundy’s giant tides. The enormous project would have dammed-up 110 square miles of coastal Maine and Canada. Moondoggle is a dramatic tale about the appeal of tidal power, the difficulties in realizing its potential, and the engineers and three U.S. Presidents (Roosevelt, Truman, and Kennedy) who tried to make clean and renewable tidal power a reality. Now on the 100th anniversary of the “Passamaquoddy Project’s” conception (1920-2020), Moondoggle—the only book on the project—explores what almost was, and what could be.