Rodrigo de Freitas Lagoon

The lagoon is connected to the Atlantic Ocean, allowing sea water to enter by a canal along the edge of a park locally known as Jardim de Alah.

The arrival of the Portuguese colonizer, Dr António Salema (1575–1578), who was at the time also the Governor and Captain General of the Captaincy of Rio de Janeiro, intended to install a sugar mill on the banks of the lagoon.

That landowner, by way of acquisition and invasion, increased the size of his landholdings in the region, in such as way that around 1620 he owned all the land from today's neighborhoods of Humaitá to Leblon.

The Prince Regent appropriated the Engenho da Lagoa (Lagoon Mill) to build a powder factory and construct the Real Horto Botânico (Royal Botanical Garden) — today's Jardim Botânico do Rio de Janeiro (Rio de Janeiro Botanical Garden).

During the 19th century many diverse solutions were thought of for the problem of stagnated water — until, in 1922, the Repartição de Saneamento das Zonas Rurais (Bureau of Rural Sanitation) presented a project to "... clean up and beautify the Capital for the Independence Centennial festivities".

In a short time, embankments formed on its edges, which gradually reduced its surface area, providing land for the Jockey Club Brasileiro, the Jardim de Alah, and the sport seat of the Clube Naval on the island of Piraquê.

However, because of poor construction quality and safety risks, after more than twenty years on the hillsides the mayor expelled all of the inhabitants and "tore down" the hills, burying a large part of the city.

It is home to a rowing stadium (Estádio de Remo da Lagoa), a paved biking path of 7.5 kilometers (more than 4.5 miles), diverse leisure equipment, and food kiosks that offer regional and international gastronomy items.

In 2015, thirteen American paddlers had stomach problems after a competition in the lagoon, which was considered a test event for the Olympics; they suffered from vomiting and diarrhea.