Machu Picchu, Iguazu, the Salt Flats in 3 weeks doesn't work
I keep seeing a lot of "2 weeks, 3 countries" type posts on here, and lots of people telling them to avoid it. And I agree with all of them.
People who've travelled Europe and done 5 countries in two weeks, great, Europe is perfect for this.
South America is not.
A few travel distances and times that people commonly assume are easy but aren't:
International arrival → Machu Picchu: land in Lima, 1 hour flight to Cusco, then a 4 hour train to Aguas Calientes. That's before you've done anything.
Atacama Desert: either overland through Bolivia, or fly to Santiago first, then a 2 hour flight up, and you're retracing your steps to get back out.
Iguazu Falls: I see a lot of Peru/Brazil trip suggestions, Lima → Buenos Aires → Iguazu, or Lima → São Paulo → Iguazu, and either way you're backtracking on yourself afterwards.
Lots of flights, big travel distances, and often you end up doubling back through the same city just to reach the next place.
South America is roughly twice the size of Europe. Western Europe fits inside Brazil alone, if that gives you a sense of scale.
Four countries in three weeks sounds achievable until you realise five full days are spent on flights, buses, taxis and checking in to hotels - rather than actually being somewhere.
The formula I use before anything else gets planned: take the number of weeks you have, subtract one, that's roughly the number of countries you can properly do justice to.
Four weeks, three countries. Three weeks, two countries.
It's not a perfect forumla, and yes the countries should ideally be next to each other, but it's saved a lot of people from an itinerary that looks great on paper and falls apart once it starts.
Want to slow down the trip even more - number of weeks - 2, so if you have a 4 week trip = 2 countries. This will allow for slow travel, and seeing more of each country rather than rushing around.
Nothing wrong with a fast paced highlights tour, but hopefully this post helps people relalise the scale of South America and what's achievable.
Happy to talk through what's realistic for whatever timeframe you've got if anyone wants a second opinion.