Explore: Survival After Airplane Accidents, Shipwrecks, Etc

Nicaragua, officially the Republic of Nicaragua, is the geographically largest country in Central America, comprising 130,370 km2 (50,340 sq mi). With a population of 7,142,529 as of 2024, it is the third-most populous country in Central America after Guatemala and Honduras. Nicaragua is bordered by Honduras to the north, the Caribbean Sea to the east, Costa Rica to the south, and the Pacific Ocean and shares maritime borders with El Salvador to the west and Colombia to the east. Nicaragua's largest city and national capital is Managua, the fourth-largest city in Central America, with a population of 1,055,247 in 2020. Nicaragua is known as "the breadbasket of Central America" due to having the most fertile soil and arable land in all of Central America. Nicaragua's multiethnic population includes people of mestizo, indigenous, European, and African heritage. The country's most spoken language is Spanish, though indigenous tribes on the Mosquito Coast speak their own languages and English. The mixture of cultural traditions has generated substantial diversity in folklore, cuisine, music, and literature, including contributions by Nicaraguan poets and writers such as Rubén Darío. Originally inhabited by various indigenous cultures since ancient times, the region was conquered by the Spanish Empire in the 16th century. Nicaragua gained independence from Spain in 1821. The Mosquito Coast followed a different historical path, being colonized by the English in the 17th century and later coming under British rule. It became an autonomous territory of Nicaragua in 1860 and its northernmost part was transferred to Honduras in 1960. Since its independence, Nicaragua has undergone periods of political unrest, dictatorship, American occupation and fiscal crisis, as well as the Nicaraguan Revolution of the 1960s and 1970s and the Contra War of the 1980s. Though nominally a unitary presidential republic, Nicaragua has experienced significant democratic backsliding since 2007 under the presidency of Daniel Ortega, resulting in large protests in 2018 and a subsequent crackdown. Following the 2021 election, it has been widely described as an authoritarian dictatorship. It is a developing country and has the second lowest GDP per capita (nominal) and fourth lowest GDP per capita (PPP) among Latin American and Caribbean countries. In 2024, Nicaragua was ranked as the second most corrupt country in Latin America, after Venezuela, by the Corruption Perceptions Index. Known as the "land of lakes and volcanoes", Nicaragua is also home to the Bosawás Biosphere Reserve, the second-largest rainforest of the Americas. The biological diversity, warm tropical climate and active volcanoes have made Nicaragua an increasingly popular tourist destination. Nicaragua is a founding member of the United Nations and is also a member of the Non-Aligned Movement, Bolivarian Alliance for the Peoples of Our America, and Community of Latin American and Caribbean States.

Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: passive sonar means listening for the sound made by vessels; active sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and sodar (an upward-looking in-air sonar) is used for atmospheric investigations. The term sonar is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extremely high (ultrasonic). The study of underwater sound is known as underwater acoustics or hydroacoustics. The first recorded use of the technique was in 1490 by Leonardo da Vinci, who used a tube inserted into the water to detect vessels by ear. It was developed during World War I to counter the growing threat of submarine warfare, with an operational passive sonar system in use by 1918. Modern active sonar systems use an acoustic transducer to generate a sound wave which is reflected from target objects.