Managua that Managua will experience a severe earthquake every 50 years or less. Managua features four smaller crater lakes or lagoons within city limits. The most centrally located is the Tiscapa Lagoon in the Tiscapa Lagoon Natural Reserve. Managua, due to its tropical climate, varied topography, naturally fertile soils, and abundant rain and water sources, boasts a great variety of flora. Many different types of trees, some of which are not found elsewhere in the world, appear, including "chilamate"s, "ceibo"s, "pochote"s, "genízaro"s, "tigüilote"s, royal palms, "piñuela"s and "madroño"s (Nicaragua's national tree) surround the city. During the rainy season (May to November),
Managua North Caribbean Coast Autonomous Region are also connected via road. A third road, currently under construction, will connect Bluefields, South Caribbean Coast Autonomous Region with Managua via Nueva Guinea. Traveling by airplane is more efficient than traveling by these roads due to the poor conditions, especially in the rainy season. Domestic flights are operated by La Costeña from the international airport. There are 36 bus routes in Managua. These are regulated by the city’s regulatory entity for municipal transports (IRTRAMMA) and individually operated by cooperatives and private companies. In addition there are two bus routes that formerly connected to outside