When people imagine Panama, they usually picture Caribbean islands, Pacific beaches, cloud forests, jungle waterfalls and the Panama Canal.
Lakes don't usually make the list.
And that's a shame, because Panama's lakes are some of the country's most fascinating landscapes. Many aren't natural lakes at all. They are enormous reservoirs created by damming rivers, and some have completely transformed the geography, wildlife and even history of Panama.
In fact, Panama's official aquatic resources authority says the country's reservoirs account for roughly 858 to 863 square kilometres of lake surface, while there are also numerous lagoons and freshwater wetlands.
And one of the world's most important lakes wasn't created for scenery, fishing or recreation.
It was created so ships could cross a continent.
Gatún Lake: the lake that changed the world
If there is one lake in Panama you should know, it is Gatún Lake.
Created by damming the Chagres River in 1913, Gatún became an enormous artificial lake and a central part of the Panama Canal. At the time of its creation, it was the largest artificial lake in the world.
And here's the strange part.
The lake exists because engineers decided that building a gigantic lake would be easier than digging an enormous canal through the mountains.
Instead of forcing ships to travel at sea level across Panama, the canal would lift them roughly 26 metres above sea level, carry them across the isthmus through Gatún Lake, and then lower them again on the other side.
So when you see a giant container ship apparently sailing through a rainforest lake, you're not imagining it.
That's exactly what is happening.
Ships travel roughly 33 kilometres across the lake as part of their Panama Canal journey.
A drowned jungle
Gatún Lake isn't simply water sitting in a natural depression.
Before the lake existed, there was a huge river valley covered in tropical forest.
When the Chagres was dammed, the water rose and flooded the valley.
Hills became islands.
Forests disappeared beneath the surface.
And an entirely new landscape was created.
Some of the islands you see today are essentially the tops of hills that existed before the lake.
One of the most famous is Barro Colorado Island, which became an important tropical research site and is now associated with the Smithsonian Tropical Research Institute.
So when you're looking across Gatún and see a forested island covered in monkeys, birds and enormous trees, you're looking at something with a fascinating geological and human history.
The island exists partly because the surrounding valley was flooded.
And Gatún isn't just for ships
Here's another surprising fact.
Gatún Lake is also part of Panama's freshwater infrastructure.
The same enormous watershed that allows ships to cross the continent provides water important for Panama City and Colón.
Every ship passing through the locks requires huge quantities of freshwater.
That means rainfall in the Panamanian rainforest isn't simply weather.
It is part of the machinery of global trade.
A tropical thunderstorm over the jungle can eventually help a container ship carrying thousands of tonnes of cargo cross the country.
That's an extraordinary connection between rainforest, freshwater and international commerce.
Lake Bayano: Panama's giant eastern wilderness
If Gatún is Panama's canal lake, Lake Bayano is its great eastern reservoir.
Created in 1976 when the Bayano River was dammed, Bayano is roughly 350 square kilometres in area and is generally regarded as Panama's second largest lake after Gatún.
But Bayano feels very different from Gatún.
There are no giant container ships crossing the middle of it.
Instead, you're surrounded by enormous stretches of tropical landscape.
The reservoir was created primarily for hydroelectric power, transforming the Bayano River into an important source of electricity for Panama.
And beneath the modern reservoir lies another story.
The creation of Bayano flooded forests, agricultural areas and inhabited territory, forcing communities to relocate. The lake therefore isn't simply an engineering achievement. It is also part of the complicated social history of eastern Panama.
The caves of Bayano
One of the most fascinating things about the region is that Bayano has caves.
The Bayano Caves lie on the southern side of the lake, adding an underground world to an already spectacular landscape.
This is one of those places that demonstrates why Panama is such an unusual country for adventure travellers.
You can go from skyscrapers in Panama City to enormous tropical reservoirs, indigenous territories, caves and jungle within a surprisingly short distance.
Lake Alajuela: the quiet lake with an important job
Then there is Lake Alajuela, another artificial lake in the Chagres watershed.
It's much smaller than Gatún, covering roughly 50 square kilometres, but its importance is enormous.
Created in 1935, the reservoir helps regulate the Chagres River system and provides water storage for the Panama Canal.
It is also connected to one of the great lessons of travelling in Panama:
water is everything.
The canal cannot operate without it.
Cities need it.
Forests depend upon it.
Agriculture depends upon it.
Wildlife depends upon it.
And during exceptionally dry periods, even the world's shipping industry starts paying attention to the water level in a Panamanian lake.
Panama has more lakes than most visitors realize
One reason lakes don't feature prominently in Panama's tourism image is that many of the country's largest "lakes" are actually reservoirs.
The country's aquatic resources authority identifies dozens of lacustrine systems, including reservoirs, lagoons and freshwater wetlands. It also notes that Gatún, Bayano and Alajuela are among the best studied because of their size and accessibility.
There are also smaller lakes and lagoons scattered throughout Panama's mountains and wetlands.
And then there is Fortuna Reservoir in the highlands of Chiriquí.
Fortuna is particularly interesting because it sits in a completely different environment from the huge lowland reservoirs. Surrounded by the wet mountain forests of western Panama, it is part of the country's hydroelectric infrastructure while also sitting inside an extraordinary cloud forest landscape.
This is where Panama's lakes start becoming particularly interesting for travellers.
A lake doesn't necessarily mean swimming
One thing visitors should understand is that Panama's major lakes are not equivalent to the classic recreational lakes of Canada or Europe.
Many are reservoirs serving critical infrastructure.
Some have complicated shorelines.
Some are surrounded by rainforest.
Some contain submerged trees and other hazards.
And some are important drinking water or hydroelectric resources.
So don't automatically see a beautiful piece of water and think:
"Fantastic. I'll get my inflatable flamingo."
Panama may have other ideas.
The wildlife around the lakes can be incredible
The tropical forest surrounding Panama's lakes can support an enormous range of wildlife.
Gatun in particular sits within the Canal watershed, where rainforest and waterways create habitat for monkeys, sloths, birds, reptiles, amphibians and countless insects.
The lake itself is also an ecosystem.
Fish, crocodilians, turtles and aquatic birds occupy different parts of the food chain.
And the islands created by the flooding have produced fascinating ecological situations because pieces of formerly continuous forest became isolated.
Barro Colorado is perhaps the world's most famous example.
Scientists have been studying its tropical forest ecosystem for more than a century, making it one of the most intensively studied tropical forests anywhere.
The strangest thing about Panama's lakes
Perhaps the most fascinating thing about Panama's lakes is that many of them are essentially artificial geography on a gigantic scale.
Imagine looking at a map of Panama and seeing a huge blue lake.
You might assume it has been there for thousands or millions of years.
But then you discover that the landscape beneath it was once a river valley covered in forest.
The islands were once hills.
The shoreline was once jungle.
And the lake was created because engineers wanted to solve a completely different problem.
In the case of Gatún, that problem was:
How do you get a ship from one ocean to another without digging through an entire country?
The answer was one of the most audacious engineering projects in human history.
Build a lake.
And today, more than a century later, ships still cross that artificial inland sea while monkeys call from the surrounding jungle and tropical rain pours into the watershed.
That is the real story of Panama's lakes.
They're not just beautiful bodies of water.
They're pieces of Panama's history, engineering, rainforest ecology and global economy all sitting in the same landscape.