While Maracaibo is commonly referred to as a lake, its current hydrological characteristics may better classify it as estuary and/or semi-enclosed bay connected to the Gulf of Venezuela.

[2] At the end of the last glacial period, the sea level rose, connecting Lake Maracaibo directly with the Atlantic Ocean,[3] and the lighter fresh water floated on the heavier salt water, causing nutrients to be deposited on the bottom of the lake,[4] resulting in the accumulation of more than a five kilometer thick deposit of sediment on the bedrock.

[2] The mountain wind from the Andes at night contacts the warm and humid air on the lake surface, forming an average of 297 mm per year.

When Italian navigator Amerigo Vespucci and Spanish explorer Alonso de Ojeda's fleet sailed here on August 24, 1499 (the first time Europeans entered this area), the stilt houses in which the Añú lived in reminded Vespucci of the Italian city of Venice, so he named the region Veneziola (Venezuela in Spanish), or "Little Venice".

The Privateer Henry Morgan raided settlements on the lake in the Spring of 1669 and defeated a Spanish squadron sent to intercept him.

[14] The 8,678-meter General Rafael Urdaneta Bridge over the lake connecting Maracaibo and Santa Rita was completed in 1962.

[7] On the northwest coast is the capital of Zulia State, the second largest city in Venezuela and an important oil export port in the world.

[23] In lakeside towns such as the city of Maracaibo, the lake water is contaminated with E. coli from feces, oil pollution, and eutrophication caused by agricultural sewage discharged into the lake, as well as domestic and industrial wastewater, resulting in the blooms of duckweed and green algae.

[24] The presence of large amounts of duckweed blocks the passage of sunlight, significantly affecting biological cycles, preventing the development of native algae and plant species.

Additionally, duckweed residues accumulate at the bottom, generating a layer of organic elements that produces large amounts of ammonium, methane and other compounds whose saturation causes eutrophication of the waters.

The blooms were noted in June to have covered 18% of the lake, and the local government had to begin spending about $2 million per month on cleanup work.

[4][14] Numerous oil spills, at least partly attributed to deficient maintenance, and the indiscriminate discharge of sewage without prior treatment, have significantly deteriorated the water quality, to the point that in some parts of the Zulia area, the water presents levels of contamination that are very dangerous for health.

Likewise, the so-called cañadas, which are random drainage courses, drag large amounts of garbage from the human settlements that are in their path to the lake.

Some primarily consist of sedimentary rock, such as the Zapara, Pescadores, and San Carlos islands (which is geographically a peninsula), while others like Toad have tectonic origins.

The majority of the islands are located in the area of the Tablazo Bay and forms the Almirante Padilla municipality [es].