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I want to ask a question about the theoretical boat.


  • Boat is coming from neutral waters
  • Boat does not want to land on Argentina or Uruguay territory purposly
  • Boat wants to cross Uruguay river
  • Boat wants to get to Brazil

The question is: which border controls boat does have to pass and in which order?

(Mostly I am interested what Uruguaian and Argentinian border controls are doing in this situation)

  • 1
    Given the river is not navigable all the way to Brazil, doesn't seem like the goal is possible.
    – CMaster
    Commented Jun 30, 2022 at 16:13
  • 4
    For starters there's a massive dam in the way.
    – CMaster
    Commented Jun 30, 2022 at 16:29
  • 1
    @CPPCPPCPPCPPCPPCPPCPPCPPCPPCPP There is this minor issue of the Salto Gande Dam so your hypothetical trip is impossible to complete no matter how navigable the river is
    – Peter M
    Commented Jun 30, 2022 at 16:33
  • 3
    Of possible interest: How do customs and immigration work in a sailboat? Commented Jun 30, 2022 at 17:28
  • 1
    FWIW If you changed the destination to Asunción on the Paraná river in Paraguay, then the premise of the question would be plausible as that river is a major international shipping route
    – Peter M
    Commented Jul 1, 2022 at 13:26

1 Answer 1


The Uruguay River is not navigable from the Atlantic Ocean to Brazil. Even before the construction of the Salto Grande Dam, there were rapids.

Encyclopædia Britannica states of the Uruguay River

Its 990-mile (1,593-km) course is interrupted by rapids between Salto (Uruguay) and the influx of the Quaraí River (Spanish: Río Guareim) near Monte Caseros; hence, its importance as a waterway is less than that of the Paraguay–Paraná river system.

That's the stretch between the Salto Grande Dam and Brazil - Monte Caseros is near the border.

  • 3
    And even if it were, rivers are not international waters, you can’t just bypass immigration by going through one.
    – JonathanReez
    Commented Jun 30, 2022 at 17:57
  • For context, it would be very useful if you indicated which edition of the Encyclopædia Brittanica you are quoting, in particular the year of publication. Are you quoting an old edition in order to indicate how it was before the Salto Grande Dam?
    – gerrit
    Commented Jul 1, 2022 at 7:03
  • @gerrit the online edition linked is dated 2022. It does not mention the Salto Grande Dam, but does say that Salto is the terminus for shallow-draft vessels. It doesn't matter for the pupose of the question whether or not the higher river level since the dam construction caused the rapids cease to exist after 1974. For one reason or another, the river was not and is not navigable to Brazil. Commented Jul 1, 2022 at 7:13
  • 4
    @JonathanReez Wether you are in international waters or territorial sea is often irrelevant for immigration purposes, as persons aboard ships are usually not subject to immigration until you actually land the ship. International ship traffic often goes through territorial waters. The ships travelling through the Sea of Marmara and the Bosporus Strait are for example not subject to Turkish immigration even if the entire area is within Turkish territory. Commented Jul 1, 2022 at 8:43

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