Iguazu borders between Brazil and Argentina
To visit both sides of the falls, one must cross the borders between Argentina and Brazil
If one is at hotels in Argentina and want to visit the iguassu falls in Brazil and vice-versa, it is possible to visit the falls without having a covid negative test. One must to bring only the covid-19 vaccine proof (two doses), they accept a digital one. Children under 12 years old don´t need it.
If one is in Foz, Brazil and visit the falls in Argentina and return to Brazil on the same day (less than 24 hours), do not need to fill in any form anymore.
Government in Argentina stop asking people to fill in forms before entering the country.
Government in Brazil is not asking for people to fill in forms anymore to enter in Brazil with passports.
Borders between Brazil and Paraguay
To enter Paraguay and travel further one needs to stamp the passport at the border and show the covide-19 three doses vaccine proof plus also yellow fever card (no need anymore to fill in the healthy declaration)
No need any requirement for children under 12 years old
More information about the requirements to cross the borders and enter in Paraguay: https://www.mspbs.gov.py/portal/22526/requisitos-para-ingresar-a-paraguay.html
For people that visit ONLY Ciudad del Este city, they don't require anything. People usually go to Paraguay for shopping because of the duty-free market.
There is a small waterfall called Monday falls near Puerto Franco town. One can also visit the Itaipu Dam from the Paraguayan side. In the city, there is also a handicraft market with souvenirs.
Note: National Park in Iguassu Brazil closes on Mondays.
For people traveling in Argentina it is better to cash dollars on the blue dollar rate. If one pays for bills using a credit card will lose money. They give a poor rate for 50, 20, 10 and 5 bills. The bills must be in excellent conditions, no marks or rips. It is better to get money in Buenos Aires, rates are better there and the WU bureaus in Puerto Iguazu always run out of money.