Hydropower remains one of the most important renewable energy sources in the world, and the largest dams showcase the scale and power of this technology. The world’s five largest hydropower dams—the Three Gorges Dam in China, the Itaipu Dam on the border of Brazil and Paraguay, the Xiluodu Dam in China, the Belo Monte Dam in Brazil, and the Guri Dam in Venezuela—demonstrate the engineering achievements and energy potential of modern dam projects. Together, they represent global efforts to generate massive amounts of electricity sustainably, though each project also carries complex social and environmental implications. The Three Gorges Dam stands as the world’s largest hydroelectric power station, with over 22,000 megawatts of installed capacity, and it serves not only energy needs but also flood control and navigation improvement. The Itaipu Dam, with 14,000 megawatts, is a model of regional cooperation between Brazil and Paraguay and remains one of the most productive hydropower plants globally. The Xiluodu Dam, at nearly 14,000 megawatts, highlights China’s strategy of reducing coal reliance by harnessing river systems. The Belo Monte Dam in Brazil, with 11,233 megawatts, has been controversial for its environmental impact in the Amazon, but it significantly adds to Brazil’s clean energy mix. The Guri Dam in Venezuela, with 10,200 megawatts, has historically provided most of the country’s electricity, though it now faces challenges from drought and underinvestment. These projects not only power millions of homes and industries but also reveal the trade-offs between large-scale renewable energy and ecological or social consequences. As symbols of national ambition and technological innovation, these hydropower dams remain central to discussions about global sustainability, clean energy, and the balance between development and environmental stewardship.