Final answer:
The Paraná River Estuary is home to the Itaipu Dam, the 2nd largest hydroelectric facility in the world.
Step-by-step explanation:
The estuary that has the Itaipu Dam, the 2nd largest hydroelectric facility in the world, is the Paraná River Estuary.
The dam is located on the Paraná River, which forms the border between Brazil and Paraguay.
Itaipu Dam has a maximum power output of about 14 GW, making it one of the largest producers of hydroelectric power.