Some of the roughly 275 waterfalls that make up Iguazu Falls. Only about 20% of the falls are on the Brazilian side. You'd never know that though unless you visited as even on the Brazilian side, the scale and enormity of the falls is immense.
Actual access to the falls is pretty straightforward. There was a bit of a line to go through at the park entrance, and then a short shuttle bus ride that brings you close to the falls, but the real trouble is getting into the country.
As an American, you need to get a Brazilian visa to enter. While the visa is valid for 10 years, it's still a hassle to get, especially in SF where the consulate is booked out several weeks in advance. Plan accordingly.
The magnificent splendor of Iguazu Falls, a UNESCO World Heritage Site.