- Where
- Río de la Plata, near the mouth of the Uruguay River
in Uruguayan waters - Coordinates
- 34.1825° S
58.2500° W - Area
- 1.84 km²
(Wikipedia) - People
- About 150 (50 families)
- Status
- Argentine territory; Buenos Aires Province
nature reserve by the 1973 treaty - Getting there
- Boat from Tigre, about 2–2½ h
or by air to the island’s airstrip - Best visited
- Year-round
The river all round was brown as strong tea with too much milk, and too wide to show its far bank. Ashore, a lane of faded pastel houses ran under big trees full of chattering parrots, past an old cinema with a grand doorway. Somewhere bread was baking. Further on stood a long, plain building with barred windows, and there I fell quiet.
The short answer
Isla Martín García is an island of 1.84 square kilometres in the Río de la Plata, the estuary between Argentina and Uruguay, near the mouth of the Uruguay River. It lies in Uruguayan waters and was long disputed between the two countries; the Treaty of the Río de la Plata of 19 November 1973 made it Argentine territory, to be used, in the words of its Article 45, “exclusively” as a nature reserve, Wikipedia records. It belongs to Buenos Aires Province and has a permanent population of about 150 people, some 50 families. The province declared it a natural reserve of multiple use in 1998, Argentine press reports. Its centre is about 48 kilometres north of central Buenos Aires, by the editor’s measurement.
Why it's worth knowing
A key to two rivers. The Spanish expedition of Juan Díaz de Solís found the island in 1516 and named it after its storekeeper, Martín García, who died on board and was buried there, Wikipedia records. Its position on the main channel, at the gateway to the Paraná and the Uruguay, made it a prize: Spain and Portugal disputed it, Admiral William Brown took it from the royalists in 1814, and in the Cisplatine War of the 1820s an Argentine fort here helped keep Brazilian reinforcements from the Battle of Juncal in 1827. Rosas, an Anglo-French force, Unitarian exiles and Giuseppe Garibaldi held it in turn in the mid-nineteenth century.
An island of prisoners. Martín García was a penal colony from 1765 to 1886, and a naval base after that. From 1879 many Indigenous people captured in the military campaigns known as the Conquest of the Desert, children and the elderly among them, were confined here and made to work; researchers have estimated that as many as 3,000 passed through in the 1870s and 1880s, and some scholars have described the island as a concentration camp, Wikipedia records. Military governments later held political prisoners here, among them three presidents: Hipólito Yrigoyen in 1930, Juan Perón in 1945 and Arturo Frondizi in 1962. German sailors were interned on the island in both world wars.
The field notes
A land border made by the river
North of Martín García, a sandbank rose from the river in the 1960s and became the Uruguayan island of Timoteo Domínguez. The 1973 treaty foresaw that the two might join, and in the 1980s the sediment between them did join them, Wikipedia records, so that the boundary across the merged island is now the only land border between Argentina and Uruguay. Uruguay has set up a working group to demarcate it with Argentina, Aduana News reported in 2026.
The village
The navy handed the island’s buildings to Buenos Aires Province in 1985, and the island became a destination for visitors, Wikipedia records. Guided walks take in the old prison, the church, the cemetery, a lighthouse of stone and brick that worked from 1897 to 1938, the old Chinese quarter, the house where the poet Rubén Darío lived, and the Cine Teatro General Urquiza, now a community hall, Argentine press and guides report. The island’s bakery is known for its pan dulce. Its forests of ceiba and laurel hold more than 250 bird species, among them hummingbirds and owls, by Wikipedia’s count.
Reed beds and forest on the island's shore, in the silt-brown water of the Río de la Plata, January 2017.
Photograph: Roberto Fiadone · CC BY-SA 4.0 · cropped
The landing: the jetty road and a blue-and-white gateway, January 2016.
Photograph: María Paula Pia, Casa Rosada · Isla Martín García, feb 2016 02 · CC BY 2.5 AR
An old tree wrapped in vines before the window of an abandoned building, May 2013.
Photograph: Silvinarossello · Isla Martín García - Árbol · CC BY-SA 3.0 · cropped
Peeling walls and empty windows in the Barrio Chino, January 2017.
Photograph: Roberto Fiadone · CC BY-SA 4.0 · cropped
- Catch the first boat out, find a seat on deck, and watch the delta thin away into nothing but water.
- Buy the sweet bread early. By afternoon my list had grown a bakery chapter, and the bakery had run out.
- Walk through the old prison slowly, and leave your jokes outside.
- Look up into the big trees and wait. Something small and bright will be looking back.
- Families live in the village all year. Greet whoever you pass, and lower your camera near their doors.
The Cine Teatro General Urquiza. The island’s old cinema and theatre, now a community hall, with an academic design and an Art Deco front on which two discs bordered with leaves and flowers flank a central pillar, Argentine press describes. It stands in the village, among the houses the navy handed to the province in 1985. It is seen from the street.
Tally, in the marginI admired its front for some time as plain decoration, all leaves and flowers. Later, thinking of the long plain building down the lane, I began to understand how much an evening out must once have meant here, and returned to look again.
Getting there
How to get there. By boat from Tigre, the delta town north of Buenos Aires. Cacciola, the long-established Tigre boat company, runs excursions to the island on set days of the week, leaving in the morning and returning in the evening, with a crossing of about two to two and a half hours through the delta and across the river, Argentine travel press reports. The island also has an airstrip, Martín García Island Airport, a former naval air station, and private flights and helicopter trips reach it.
When to go. Year-round. Summers are hot, with average summer temperatures of about 29 °C by Wikipedia’s climate figures, and winters mild. Rises of the Río de la Plata bring flood warnings to the estuary at times, Perfil has reported; check before travelling.
What to arrange ahead. The boat excursion, which runs only on certain days; most visitors come for the day.
Safety. The State Department has Argentina at Level 1, exercise normal precautions (advisory dated 10 July 2026 in its feed, read 5 October 2026). It notes petty crime in tourist areas and Buenos Aires, a low-risk health notice for Andes virus, and crime and violence by trafficking groups in Rosario, about 260 kilometres from the island by the editor’s measurement. The hazards here are the place’s own: heat, insects and the river.
Mark this place
Common questions
Where is Isla Martín García?
Isla Martín García is a small island in the Río de la Plata, near the mouth of the Uruguay River, about 48 kilometres north of central Buenos Aires. It lies in Uruguayan waters but is Argentine territory, part of Buenos Aires Province, under the 1973 Treaty of the Río de la Plata.
Why is Isla Martín García Argentine if it is in Uruguayan waters?
The 1973 Treaty of the Río de la Plata settled a long dispute by recognising Isla Martín García as Argentine territory within Uruguayan waters, on condition, in its Article 45, that it be used exclusively as a nature reserve; in return Argentina made concessions elsewhere in the estuary, including Juncal Island.
Which presidents were imprisoned on Isla Martín García?
Three Argentine presidents were held on Isla Martín García by military governments: Hipólito Yrigoyen in 1930, Juan Perón in 1945 and Arturo Frondizi in 1962, according to Wikipedia.
How do you get to Isla Martín García?
By boat from Tigre, north of Buenos Aires: the Cacciola company runs day excursions on set days, a crossing of about two to two and a half hours. The island also has an airstrip, Martín García Island Airport, used by private flights.
Does Isla Martín García have a land border?
Yes. A Uruguayan island, Timoteo Domínguez, rose from the river north of Isla Martín García in the 1960s and joined it in the 1980s, so the boundary across the merged island is the only land border between Argentina and Uruguay.
How many people live on Isla Martín García?
About 150 people, some 50 families, live permanently on Isla Martín García, according to Wikipedia. The island has a village with a bakery, a church and a community hall in its old cinema.
What happened to Indigenous prisoners on Isla Martín García?
From 1879, many Indigenous people captured in Argentina’s military campaigns known as the Conquest of the Desert were confined on Isla Martín García and made to work. Researchers have estimated that as many as 3,000 passed through in the 1870s and 1880s, and some scholars describe the island as a concentration camp, Wikipedia records.
Who was Martín García?
Martín García was the storekeeper of Juan Díaz de Solís’s Spanish expedition, which reached the island in 1516; he died on board and was buried on the island, which was named after him.