If you are traveling between Buenos Aires and Uruguay, even for a day trip, chances are that you will at least look at taking the ferry across the Río de la Plata. Dan & I have done it a few times, and its much easier than one would think. Its also much quicker than flying between countries considering the time getting to the airport, security, etc.
THE BASICS
Buenos Aires (BA), Argentina is quite close to Uruguay, only separated by the Río de la Plata. As such, a common and convenient way to get between BA and Uruguay is to take the ferry, generally referred to as the “BuqueBus,” between the two countries.

Busy BA…

To sleepy Western Uruguay…
In fact, ferries depart several times a day between BA and Colonia, Uruguay and BA and Montevideo, Uruguay and back. The journey to Colonia takes a little over an hour, while the journey to Montevideo takes around 3 hours.
THE THREE FERRIES
There are three ferry companies running the BA/Uruguay route as of 2019 – BuqueBus, SeaCat, and Colonia Express. In short, all depart from the BuqueBus terminals and often you will buy a ticket for one ferry, but get placed on another. However, this is more common to happen when you buy a SeaCat or Colonia Express ticket and get placed on the BuqueBus (rather than the other way around).
BuqueBus
The BuqueBus is the largest of the ferries, carrying lots of people and cars. Since this is more of a ship than a boat, the ride is quite smooth, even on rough days, making it the best choice for those susceptible to seasickness. It actually reminded me of one of the large ferries that travels between the Greek Islands. Most BuqueBus ferries have at least two floors for people, with walk-in Duty Free shops and a cafe serving food and drinks. The seating is generally airplane style and spacious, and there is a lot of room to store personal belongings. In addition to the airplane style seating, there are usually a few tables near the cafe.
SeaCat
SeaCat is often cheaper than the BuqueBus and its own branded boats are much smaller. The SeaCat ferry does not carry vehicles and since its small, is bumpier than the large BuqueBus. Seating is airplane Economy style with minimal room for personal belongings. There is usually a small Duty Free shop on the SeaCat and a small concession stand.
Colonia Express
The Colonia Express is the most modern of the three ferries, and its also the smallest and the fastest. Its actually more of a speed boat than a ferry. Since its small and fast, some people prefer it for the shorter journey. However, the Colonia Express is rumored to offer a bumpy ride (a problem if you get seasick) and if there is bad weather, it is often cancelled. I have never taken the Colonia Express, so I cannot vouch for the trip it provides. It does, however, look very sleek!
BUYING A TICKET
The first step in taking the ferry between BA and Uruguay, whichever the company, is to purchase a ticket. Tickets can be purchased same day at the BuqueBus Terminal; however, its quite easy to purchase a ticket online and recommended, as they can sellout. To purchase a ticket, visit the BuqueBus website (or one of the other companies websites, listed below), set the language to English if you do not speak Spanish, and enter the destination and return date; its very straightforward. The website will then prompt you to create an account, which is required to collect your tickets.
To complete the purchase, you must enter your passport information and pay via credit card. As with a lot of transportation, ticket prices generally increase the closer you are to departure. You should receive a link to your tickets via email within 24 hours. Print before departure and, voila! Note – when we last took the BuqueBus in November 2018, no one used their cell phone to pull up tickets; everyone printed them.
CHECKIN AND LUGGAGE

Checkin at the BuqueBus Terminal in BA.
On the day of departure, arrive at the BuqueBus Terminal at least one hour before departure (BuqueBus recommends 2 hours) and present your printed ticket at checkin with your passport. And yes, a passport is required even for day trips between the countries.
Side note – all of the ferry terminals for BuqueBus, SeaCat and Colonia Express, are referred to as the BuqueBus terminal. The BuqueBus Terminal in BA is in Puerto Madero, the BuqueBus Terminal in Colonia is known by everyone in the area, and the BuqueBus Terminal in Montevideo is near the old town port (very close to the Mercado del Puerto).
On arrival, a ticket agent will replace your printed ticket with a page of blue tickets containing your name and information. If you have luggage to check, it will be tagged and checked here! And, its just like an airport – place your bag on the scales and the ticket agents tags your bag.
And on the luggage note, the BuqueBus website states that it allows 1 checked luggage of up to 20kg and 2 carry-on pieces of luggage. However, in practice, I did not see this being strictly enforced but, we were traveling on a large BuqueBus ferry. I would be more cautious on the smaller ferries. For reference, we each had full suitcases that we checked and each carried on a backpack. I also carried on a Longchamp purse. No one said anything about the quantity or weight of our luggage.
CUSTOMS
After checking in and getting those blue tickets, you will go through Customs, which consists of running all of your luggage through an X-ray machine. Its just up the stairs in the BA terminal. This was pretty quick and I did not see anyone getting stopped, but apparently they are particularly interested in stopping people with prohibited food goods – such as raw meat, etc. Check the most recent Customs information for prohibited foods.

Customs.
IMMIGRATION
Directly after Customs is Immigration. Line up like you would at the airport. First up, the country you are departing. Then, directly after, the country you are entering. Literally, they Argentinian and Uruguayan Immigration officers share a booth, so its super easy! I have moved between Argentina and Uruguay 3 times via the BuqueBus and I have never been asked any questions by either official. I would note that both countries stamp your passport. As such, ensure you have enough space in your passport. For example, if you are doing a day trip to Colonia from BA, you will need to have space for 5 passport stamps just for the day trip!

Lines for Immigration. We have never seen a line in BA, but there is often one in Colonia, especially on the late evening departures for the day trippers.
WAITING FOR DEPARTURE
After checking in and clearing Customs and Immigration, its time to wait for the ferry! In BA, there is a pretty nice waiting area with lots of seating, nice WCs, a small café, and a small gift shop. We did not board until the time we were scheduled to depart, but people started lining up to board about 20 minutes in advance. I guess they wanted those window seats! And, to be clear, it is usually necessary to line up if you want a window seat.

Restaurant/lounge area.

Lots of signs in Spanish and English.

More waiting room.
I have not been to the ferry port in Montevideo, but in Colonia it is similar to BA, just smaller. I would also note than in departing Colonia, the ferry port is significantly smaller than that in BA, and there are a lot of people in a tiny space. As such, I would closely adhere to whatever time frame Uruguayan officials suggest regarding catching the ferry to BA. The last ferry of the day is particularly chaotic as day trippers are leaving to go back to BA.
THE RIDE
The ride between Argentina and Uruguay is pretty uneventful and there really is not that much to see. In both the BuqueBus and the SeaCat, seating is airline style with first come, first serve seating. If you want a window seat, get in line early.

Boarding!

General seating – kind of looks like an airplane.
In addition to seating, shorty after departure the duty free shop opens, which was two whole floors on my BuqueBus! There were also two snack shops on my BuqueBus, serving a limited selection of candies, chips, drinks (including wine and beer), and sandwiches and salads, with even a few hot food varieties. Credit card was accepted for even my small purchase of waters and a cookie.

Some different seating.

The Express Bar, serving food and drink.

Duty Free Shop.

Some odd seating at the back of the boat.

2 floors.

Small game room.

Another cafe with to go snacks.

Had to get an Alfajore before I left Argentina! Luckily, they sold them on the boat!
DEPARTURE FROM THE FERRY
When the ferry reaches its destination, everyone de-boats and luggage is placed on a conveyor belt, just like at the airport except a bit quicker. Pick up your bag, send it through the Customs machine again, and you are on your way!

Departing the ferry. Not very glamorous…

Picking up our luggage.
EXPLORING THE TOWN
In BA, the ferry terminal is in the heart of the city and there will be taxis waiting outside. Uber also works. As such, its pretty easy to get to your destination. You can also walk to most places in Colonia (just be careful of the traffic!).

Ferry terminal in Colonia. Loved being welcomed by Jacaranda trees in bloom!
In Colonia, the Old Town is about a 10 minute walk from the ferry terminal, and almost everyone will be making this walk; follow the crowd. If you are going further afield from Colonia, I recommend booking a car to collect you in advance or planning to rent a car. Colonia is rather remote and neither Uber nor taxis are plentiful.
THE FERRY FROM TIGRE TO CARMELO
I will also mention that there is another ferry – the Cacciola Ferry – to Uruguay from Tigre (a neighborhood about an hour outside of BA) to Carmelo, Uruguay, an hour West of Colonia. I have not used this ferry, but they have a website. While we did stay in Carmelo, we took the ferry to Colonia and a car to Carmelo (at a cost of $100 US), as this ferry was not running on Thursday mornings when we needed to travel.
STEAL OUR TRIP
BuqueBus: English website for purchasing tickets.
SeaCat: English website for purchasing tickets.
Colonia Express: English website for purchasing tickets.
Cacciola Ferry: Website for purchasing tickets. English option is iffy. If your purchase will not go through, it probably means the ferry is not running that certain date.
Dear Sir or Madam: Would you know the address of the ferry terminal in B.A. and how to get there.
Is it close to the J. Newberry airport.I thank you for your reply.
Hi Gerhard, The ferry terminal’s website is here, with its address, etc.: https://www.buquebus.com/english/about-us/terminals. Its referred to as the Buquebus Terminal. Its not too far from the J. Newberry Airport (prob. 25 minutes in a taxi), but you cannot walk unless you have a lot of time and very little luggage. I recommend taking a taxi. I would give extra time between the airport and the ferry terminal, because traffic in that area can be crazy. Hope this helps!