You cannot reasonably walk from the Argentine side of the park to the Brazilian side. You would either take a taxi or use the public buses. The Brazilian side of the park and the Argentine side of the park (and the respective towns)are separated by the river which forms the falls. Each side of the park is a bit distant from the respective town, and each airport lies between the town and the park entrance. (I suspect you can Google for a map that will illustrate this.)

By bus, from the Argentine park entrance, you would take the bus to the bus station in the town of Puerto Iguazu. Then you would take the bus that goes across the border to the bus depot in the Brazilian town of Foz do Iguacu. From that bus depot (or where the bus intersects the route of the "border crossing" bus, closer to the park entrance), you would take a bus to the park entrance on the Brazilian side.

Early in the morning, a taxi from the Sheraton to the IGU Brazilian airport might take about an hour if traffic is not backed up. Border inspection is usually cursory, but you would get your passport stamped on entry to Brazil. I would have the hotel order you a taxi a day beforehand. (Note: YOu do not have to go through the Brazilian side of the park.)

Thanks for the reply. I was thinking there was some sort of walking bridge between the two sides but it does not sound like that. So - when people say make sure you see both sides of the falls -- how do you do that? Do you have to take a bus or taxi to go from the Argentina side of the park to the BRazil side? And -- how long does that take?

Yes, buses run between Puerto Iguazu and Foz do Iguacu, but a taxi is probably easier and quicker - it will only take about 30 mins from park entrance to park entrance.

Thanks so much for the info. I have one more thing. I need some guidance on the best route here. I am a 50ish woman who will be doing this leg of my trip solo. I will be concluding a trip to Antartica on a Sat in Feb. in Buenos Aires. I get in at 1 PM. I have a flight book to Iguazu, Argentina at 4 PM. So, I will be getting to the Sheraton in the park in the evening. I understand the park is closed -- so I won't really get to do anything that evening except watching the falls from the hotel. I have all day Sunday. Then on Monday I can either take a 930 AM or 330 PM to Rio. The flight leaves from the Brazil side. My flight back to the US is 930 PM on Tuesday. I would like to see both the Argentina and BRazil side of the falls. On the Argentina side I would like to do a bit of hiking and also take a boat ride. In Rio, I am looking for a boat ride around the bay for a few hours and am also looking to get on an organized tour to the major sites. I am stuck on 2 things. First -- given that I would need to take a cab over to the Brazil side of the falls, would it be better to just spend Sunday night on that side? And -- would you suggest that I leave at 930 AM or 330 PM on Monday given the activities I hope to explore.

There are three trails on the Argentine side--upper falls, lower falls, and the Devil's throat (the latter can be reached via tram to the trail head). Completing these three circuits at a leisurely pace (the only way to experience the falls imo) and the zephyr ride under the falls requires the better part of a day, leaving no time to explore the Brazil side.

I suggest staying the night at the Sheraton and taking a cab across the next morning to see the Brazil side, leaving in time for the 3:30 flight.

"I have all day Sunday. Then on Monday I can either take a 930 AM or 330 PM to Rio."

Is Monday the only day you have for Rio?

See some of the Argentina side on Saturday evening, maybe the lower trail. Sunday, take the upper trail and do a boat ride under the falls. If time, relax along the river in the shade, watching the aggressive coatis. Monday, take the later flight to Rio. Take your luggage to the lockers at the Brazilian park entrance, planning to arrive at park opening to maximize your time (have the hotel pre-order a taxi for you), and spend a couple of hours taking photos along the path. If there is time, go to the bird park near the park entrance. The sirport is not far from the park entrance, but plan to arrive at least an hour ahead.

If Monday is your only Rio day, I would do the upper trail in Argentina on Sunday and then go over to the Brazilian park to take pictures along the walkway and maybe see the bird park if time. I would stay in Foz overnight. Then I would take the earlier flight to Rio and hire a tour guide with car to take you around Rio most efficiently. (In that case, I recommend Rafa http://donrafaguestsinrio.blogspot.com/)

In Rio, the easiest boat ride is the (12 minute)commuter ferry over to Niteroi from Praca XV, and very inexpensive too. There's a great view back over to Rio. You can see the museum in Niteroi while you're there. To get to sights such as Corcovado/Cristo and Sugarloaf, you can easily take a regular yellow taxi.

If you must leave out something in order to catch the early flight, under no circumstances should you omit the Devil's Throat...The Devil's throat will place you literally at the top of the most powerful section of the falls, an experience not to be missed.

Since the Brazil side's focus is more on a panoramic view, I would opt to go on the lower trail and the Devil's throat rather than the upper trail...very different perspective, one you will not find on the Brazil side. Sign up for a boat ride at a time that coincides with your lower trail jaunt...the ride itself is not very time consuming and will be the highlight of your time in the park.