There used to be a (cheap) train two times per week from Buenos Aires Federico Lacroze railway station to Posadas, named "The grand captain". Do to a jurisdictional limbo this railway is out of order since 2011. For more information visit http://www.sateliteferroviario.com.ar/horarios/posadas.htm
Aeropuerto International Cataratas del Iguazu (IATA: IGR) (ICAO: SARI) is close to the waterfalls and to the city of Puerto Iguazu. There are several flights a day from Buenos Aires serviced by Aerolineas Argentinas  and LAN Chile .
Go from the airport to the bus terminal:
taxi: 120AR$, in front of the airport.
minibus: 60AR$, inside the terminal you can buy a ticket and catch the bus in the front of the airport. (July 2014)
Go from the bus terminal to the airport
taxi: 80AR$, you can ask to the taxi desk at the terminal to call a taxi for you.
minibus: you must ask at your hostel and reserve in advance.
Foz do Iguaçu International Airport (Brazil) is another way in but from Brazil. Some people travel to Foz do Iguaçu International Airport but stay on Puerto Iguazu (Argentina). Be aware that there is a immigration point between Argentina and Brazil, so keep all the documents they give you at the airport and at immigration. The cost of going by taxi from Foz do Iguaçu International Airport in Brazil to Puerto Iguazu is around 40usd. You can ask for a taxi inside the airport and pay cash or on credit card. Taxi drivers know the immigration regulations so they will walk you by the customs to enter Argentina. By taxi the drive is no more than half an hour, but be advised that sometimes they may be lots of people on the immigration point and at peak hour you can expect 45 minutes or an hour waiting lines. Also be aware that some taxi drivers from the Brazil side may not be familiar with street addresses in Puerto Iguazu, so it is a good idea to check out where you're headed on a map first.
A one way bus ticket from Buenos Aires to Puerto Iguazu costs about 800 pesos (April 2013, though by browsing around retiro you can find discounts and we went for 530 pesos each). For as low as 1300 pesos you can get a 7 day tour including return bus ticket, four nights in a hotel, excursions, some meals.
Access Puerto Iguazu from Peru, Bolivia, Chile, Brazil and other parts of Argentina by bus passes offered by the Green Toad Bus. They also offer bus tickets online from Buenos Aires, Salta, Sao Paulo, Florianopolis, and Rio de Janeiro to Puerto Iguazu. []. Long distance and local buses arrive to the Terminal de Autobuses on Av. Cordoba.
From Foz do Iguaçu: take a bus to the border (4 reals), get your exit stamp and get the next bus to the Argentinian side where you'll get an entry stamp for Argentina. Buses to and from Argentina will stop at the Argentinian border for immigration control, however they will not stop for the return back through the Brazilian border as most of the passengers are Brazilians. Check with your driver if he or she doesn't mind waiting 5 minutes, especially if you're getting a bus close to the end of the day. Many drivers will refuse to wait, but will offer you a ticket to get on the next bus free. Be aware that this is only valid for the same company and the next bus can take 15-30 minutes to arrive.
A bus leaves twice hourly from the terminal to the entrance on the Argentine side of the falls (60 Pesos return at Feb2013). Most hotels have the timetable. Tell the bus driver if you want to stop along the way.
Frequent buses cross the border to Foz do Iguaçu where you can change to a bus to the Brazilian side of the falls
Some buses cross to Ciudad del Este without stopping in Brazil (hence, no need for Brazilian im- and emmigration)
There is a ferry crossing directly to Paraguay (look for the sign on the corner Av. Missiones and Brasil). About twice hourly during daylight. 10 Pesos for foot passenger. On the Paraguayan side walk up to the main street and take any bus going to the right (don't believe "Taxi" drivers telling you there is no bus, they are just up to overcharging you). You can pay the ride in pesos (2 Pesos). When you arrive at the roundabout about half an hour later you are in the centre of Ciudad del Este, for the bus terminal you have to get off earlier.
Taxis operate with fixed prices which makes the distance to both parks from your hotel irrelevant. A trip from your hotel in or near Puerto Iguazú to the Argentine park or vice versa costs 60 AR$. Round trips are advertised as double but most taxi drivers will do the trip for 100 AR$ if asked. Do not be amazed if the very same driver waits for you for hours. Taxi drivers will store your luggage in their taxi while waiting. A round trip from your hotel to a supermarket in Puerto Iguazú costs 10 AR$.
Three Frontiers Landmark, (walk down Av. Tres Fronteras). Have a look at Argentina, Brazil and Paraguay, all in the same glimpse of the eye while there are cargo freighters making slowly their way along the water.free. edit
Güira Oga, . 9h-16h45 (winter); 8h30-18h30 (summer). Visit a refugee of animals such as the Toucan, a caiman and a lot more! There is a bus that goes from the center. Ask your hostel or in the bus station.75 pesos (July 2013) guided tours only (tours in english at 10h, 12h, 14h and 16h). edit
See the falls in the morning to ensure that you can hike the island trail which requires a boat trip across the river. It is not advertised, but the boat trip is included with your entrance ticket, but only runs for the first 1,000 passengers, or until 15:15. Yesterday, it was closed at 11:45. If you want to see the falls for two days, your second entrance is half off, but you will need to show ID at the end of the first day to get a stamp on your ticket. The next day will be half priced.
La Rueda, Av. Cordoba. Excellent food, and probably the best restaurant in Puerto Iguazú esthetically. The Pollo al Diablo (Chicken Devil's Style), Surubi al Diable or La Rueda Salad are delicious. English spoken. Accept cash and credit cards.edit
La Vitrina, Av. Victoria Auirre 773, ☎ ''+54'' 3757-422165 (firstname.lastname@example.org). Go there for the Asado prepared on the big outdoor barbecue. They have good salads, pasta, empanadas, etc. But the bife de chorizo, asado de tira, etc is what set La Vintrina apart from other places.edit
Aqva, Av. Córdoba y Carlos Thays, ☎ ''+54'' 03757 422064, . Excellent food, many options of dishes with local river fish and Argentinian beef, of course. Extensive wine list. Reservations recommended on weekends. Opens everyday for lunch and dinner. Accepts major credit cards.edit
Beware that the hostels in Puerto Iguazú seem to be experiencing something of a bedbug epidemic. Check reviews on tripadvisor, etc. carefully before booking.
Hostel El Güembé. El Urú 120, Puerto Iguazú. 03757-421035. (email@example.com). Small, friendly and relaxed hostel, offering both shared and private rooms. Dorms 70 AR$. In a very nice, tranquil and green part of town, only 5 min. from the bus terminal. Includes breakfast and free WiFi. Good kitchen.
Hostel Irupe, Avenida Misiones Nº 80 (100m off the bus terminal), ☎ +54 (03757) 423618, . checkout: 10am. Cheap, but clean hostel, 30 AR$ p.P. for double with bathroom (May 2009); kitchen available, only a few steps away from the main bus terminal. Dorms for 30 pesos p.p. One computer with internet but no wifiedit
Was closed on Feb2013.
Hostel Inn Iguazu, Ruta 12 Km 5, Puerto Iguazú, ++54-3757-421823, . Dorms US$11 (members). Has a pool and tiki bar, air-conditioned rooms, a young, partying crowd, nightly events, daily sports games, free internet, free breakfast, bar and restaurant. You can get there by taking the bus that goes to the falls (leaving from the terminal).
Marcopolo Inn Iguazu, Av. Cordoba 158, 3370, Puerto Iguazu, Argentina, . Marcopolo inn Iguazu is located 20m from the Bus terminal and 2 blocks from the Commerce center of Puerto Iguazu. Internet access, kitchen, breakfast included from US$14.50(dorms) and $28(private). 6/2013edit
Pousada Timbó, Av. Misiones 147, Puerto Iguazú (5 min. walk down Av. Misiones from the bus terminal.), ☎ ++54 3757 422 698, . Good and centrally located hostel with dorms on the rather big side - number of beds as well as space. Free internet, welcoming, breakfast included. US$13. edit
Residencial Uno, Fray Luis Beltrán 116, Puerto Iguazú. +54-3757-420529. (firstname.lastname@example.org). Warm and comfortable hostel in the heart of Puerto Iguazú. It offers private rooms, breakfast, free internet access & wi-fi area, swimming pool, air conditioner, BBQ area, Cable TV & DVD lounge, among others services. Two blocks from the bus station and less than 5 minutes from downtown. Dorms from US$12. Doubles from US$25. Minihostels.com members get 10% off.
Stop Hostel (Stop Hostel Iguazú), Av. Victoria Aguirre 304, Puerto Iguazú, Argentina, ☎ +54-3757-15547709, . checkout: 10:00. Stop Hostel is located 25 minutes away from the falls, Dorms from 10 USD, includes air condition, breakfast, black hairy fungies in the very bad kitchen, smelly beds with bedbugs and bored staff. See tripadvisor or similar webpages for its bad references. Stay away! edit
Garden Stone Hostel, Av. Córdoba Nº 441 - Puerto de Iguazú (Three blocks north from the bus terminal along Av. Córdoba), ☎ +54 (03757) 420425, . checkout: 10:00 am. A new hostel (March 2010), quite nice, peaceful, clean. Dorms from US$9. There is a little garden and a kitchen. Includes WiFi, large lockers in rooms, and poor breakfast, do not have even a toaster available. Toilets very basics and showers with not really hot water. you will wait until 9:00 AM in order to take a shower and don't freeze trying it. edit
Hostel Bambu Club, Av. Córdoba Nº 445 - Puerto de Iguazú (2 minute walk from the bus terminal along Av. Córdoba), . checkout: 10:00 am. A new hostel (February 2011), this is a party hostel with huge pool and bar area that packs in a crowd, plus very clean and friendly. Includes WiFi, lockers, and breakfast.edit
Americano, Ruta 12 Km 5, Puerto Iguazú, (03757) 420 190,. Used to be called El Viejo Americano, and used to be cheaper. It is a camping (26 pesos per tent plus 26 pesos per person). There are also bungalows and normal rooms. You can get there by taking the bus that goes to the falls (leaving from the terminal, 1.50 pesos). There are pools, a restaurant, convenience store and soccer fields, which are all very well maintained. Many fire pits for barbecues and other niceties. Bugs galore so bring plenty of repellent.
CAMPING CLOSED , ONLY ACCOMMODATION NOW ( april 2013)
Hostería Los Helechos, Paulino Amarante 76, Puerto Iguazú. 03757-420338, . Very centrally located hostel, just two blocks from the bus station. Lots of facilities including swimming pool.
Hotel Tierra Colorada, El Urú 28, Puerto Iguazú. 03757-420649. Pleasant and friendly small hotel, comfortable rooms.
Hotel Los Troncos, San Lorenzo 154, Puerto Iguazú. 03757-424337, . Very good hotel. Wonderfully located on the edge of the city (about a 15-minute walk from the bus station). Gives you the feeling of staying in the middle of a tropical rain forest. The staff are extremely nice. The hotel is well facilitated: there is a nice pool, continental buffet breakfast and the "cabañas" have air conditioning, digital television and a balcony. Ask the staff for a trip to the Brazilian side of the falls: they have contacts with drivers who take you there, wait for you and bring you back to the hotel again for ARS140 in total (fixed price, no price per person).
SecretGardenIguazu B&B - A three room affair, conveniently located in the town of Puerto Iguazu. High on concept the secret garden is populated by tree ferns and other shade-loving plants salvaged from the slash and burn rural and logging activities decimating the surrounding rain-forest.
Vice Consulate of Brazil (Vice-Consulado em Puerto Iguazú), Av. Cordoba 264 C 3370, ☎ +54 3757 420-192 (email@example.com, fax: +54 3757 422-494). Brazilian visas can be obtained here. As at Jan 2012, you need a bank statement, proof of entry (flight/bus ticket) and exit (from the North/South American continent is OK, i.e. a flight out of New York is OK), printed online form and a photo. Processing in one day, 90 day multiple entry given. (385 pesos for Australians.) (800 pesos forUS citizens). Signs at the embassy say it can take up to 72 hours to process the visa, but most are done within 24 hours. They only accept applications from 8am till 12pm (sometimes only until 11 am) so make sure you get there early.edit