Floating Cities – The Islands of the Uros and the Aztec city of Tenochtitlan

By Visio Roughton

Many cultures have learned to adapt to their environments, living alongside rather than against them. These civilizations, both ancient and modern, reflect the true power of human ingenuity. Two examples of this can be found in the floating islands of Lake Titicaca with its floating islands built by the Uros people, and in Tenochtitlán, the city built on a lake that stood as the heart of the Aztec empire. These civilizations were able to accomplish such architectural achievements without the use of modern technology or tools, further demonstrating the incredible capabilities of human innovation.  

Manmade Islands – Lake Titicaca

Lake Titicaca is situated high in the Andes Mountains on the border of Bolivia and Peru. Sitting at nearly twelve-thousand feet above sea level, it is not only the largest lake in South America, it is also the home to one of the most remarkable displays of human-made landscapes. 

Located throughout the Peruvian side of the lake (mainly off the coast of Puno, one of the lake’s main cities) are islands of the Uros people. They have lived on the floating masses for generations.  

According to stories, the islands originally served as a refuge. It is believed that the Uros first built the islands centuries ago after being driven from their land by the growing Inca empire. By living on the water, they could avoid the threat of their aggressive neighbors. 

Originally, and for a large part of their history, the islands were located about nine miles from shore, almost in the middle of the lake. However, after a storm in 1986 that destroyed a majority of the islands, the Uros made the choice to rebuild their community closer to shore. Today they reside just three miles away from the Puno port. 

The islands themselves are built out of totora reeds, a plant that grows abundantly in the shallow waters of the lake.

To construct the island, layers of the reeds are tightly woven with totora roots; while the reeds provide initial support, as the roots grow, they also work to hold the reeds together. Once completed, the islands are strong enough to support multiple families, their homes, schools, and even in some cases, small livestock. The reeds are stable enough to support the weight from the community above them, while also being buoyant enough to remain floating above the water. To keep the islands from floating away, eucalyptus rods are driven into the lake bed to act as an anchor before then being tied to the roots of the island. 

The Uros use the same type of reed used to build their islands for other purposes too. The reeds themselves are used to build houses, boats, mattresses, and many more things. Totora reeds can also be eaten, and they often are. They are also used for medicinal purposes and the totora flowers are used to make tea.

Once an island is built, it will typically last for twenty-five years before the residents construct a new island and leave the old one.   

Tenochtitlan – Lake Texcoco:

In the early 14th century, a group of people known as the Mexica settled on a swampy island in the middle of Lake Texcoco. 

It is said that they were guided by a prophecy: the wandering tribes of the Mexica would know where to build their city when they saw an eagle perched on a cactus, devouring a snake. When they finally witnessed this sign, they began constructing the city that would one day become  Tenochtitlán, the heart of the Aztec Empire. At its height, Tenochtitlán was home to an estimated 200,000 to 400,000 people (though most estimates place the number closer to 200,000). It also grew to be one of the biggest cities in the world at the time.

They began construction of the city on a small island in the middle of Lake Texcoco —which at its largest, was 2,189 square miles wide with a depth of 500 feet). As the city population grew, they expanded the surface area of the island (it’s theorized they did this via the distribution of rocks and silt). In addition to the land expansion, they also developed an extensive system of canals, causeways, and more artificial islands. These waterways were not only practical but stunning as well. In fact, upon their arrival at the city, Spanish conquistadors likened Tenochtitlán to Venice, Italy. 

Of all the innovations made in Tenochtitlán, the most notable achievement comes in its agricultural system. Though the city was built in the middle of Lake Texacoco, the chinampas (sometimes referred to as floating islands) were utilized to grow crops at a capacity that could feed the city’s flourishing population.  “Floating gardens” is truthfully a misnomer, as the gardens were not really floating in the water. They were actually the result of the building up of layers of soil, reeds, and other aquatic vegetation, that accumulated within fences that were made of reeds woven together with stakes in the lake bed. 

Though it took time, the islands eventually built up enough material to provide an ample environment to plant crops. Once functional, the chinampas quickly became a vital resource for feeding the people of Tenochtitlán. Not only could they yield multiple harvests per year, but they could also sustain crops like maize, beans, squash, tomatoes, and chilies. In addition to their agricultural benefits, the chinampas also helped regulate Lake Texacoco’s water levels and prevented erosion. 

After the Spanish conquest, and the destruction of Tenochtitlán along with its water management systems, Lake Texcoco eventually drained to a minuscule portion of what it once was. This, in turn, left the Tenochtitlán’s chinampa system abandoned. 

Today, the ancient farming technique is still used in some areas of Mexico. In Xochimilco, located in Mexico City, some farmers continue to use chinampas for their crops, although the practice is dwindling. While some remnants of Lake Texcoco are still present, the majority of the lake basin has largely drained and is now occupied by Mexico City.