Question: What type of land mass was discovered in 1513 by a Spanish explorer, governor, and conquistador?

Context paragraphs:
History of Florida: The history of Florida can be traced back to when the first Native Americans began to inhabit the peninsula as early as 14,000 years ago.  They left behind artifacts and archeological evidence.  Written history begins with the arrival of Europeans to Florida; the Spanish explorer Juan Ponce de León in 1513 made the first textual records.  The state was the first mainland realm of the United States to be settled by Europeans.  Thus, 1513 marked the beginning of the American Frontier.

Hernán Venegas Carrillo: Hernán Venegas Carrillo Manosalvas (Córdoba, ca. 1513 - Santa Fe de Bogotá, February 2, 1583) was a Spanish conquistador who participated in the Spanish conquest of the Muisca and conquest of the Panche in the New Kingdom of Granada, present-day Colombia.  Venegas Carrillo was mayor of Santa Fe de Bogotá in two terms; in 1542 and from 1543 to 1544.  Between the two terms, the post was filled by Juan de Céspedes.  Conquistador Pedro Fernández de Valenzuela was his cousin.  In total Hernán Venegas Carrillo got twelve children, four with Magdalena of Guatavita, the sister of the last "zipa" Sagipa and eight with his second wife, Juana Ponce de León y Figueroa, daughter of the governor of Venezuela Pedro Ponce de León.  Venegas Carrillo is buried in the Primatial Cathedral of Bogotá, located at the Bolívar Square in the centre of the Colombian capital.

History of the Panama Canal: The idea for a Panama canal dates back to the 1513 discovery of the isthmus by Vasco Núñez de Balboa.  The narrow land bridge between North and South America houses the Panama Canal, a water passage between the Atlantic and Pacific Oceans.  The earliest Central American European colonists recognized this potential, and several proposals for such a canal were made.

List of Russian explorers: The history of exploration by citizens or subjects of the Russian Federation, the Soviet Union, the Russian Empire, the Tsardom of Russia and other Russian predecessor states forms a significant part of the history of Russia as well as the history of the world.  At 17075400 km2 , Russia is the largest country in the world, covering more than a ninth of the Earth’s land mass.  In the times of the Soviet Union and the Russian Empire the country's share in the world's land mass reached 1/6.  Most of these territories were first discovered by Russian explorers (if indigenous peoples of inhabited territories are not counted).  Contiguous exploration in Eurasia and the building of overseas colonies in Russian America were some of the primary factors in Russian territorial expansion.

Isabel de Tolosa Cortés de Moctezuma: Dona Isabel de Tolosa Cortés de Moctezuma (1568- 1619/1620), was a wealthy Mexican heiress and the wife of conqueror and explorer Don Juan de Oñate who led an expedition in 1598 and founded the first Spanish settlement in what is now the state of New Mexico.  She was the granddaughter of Spanish explorer and conquistador Hernán Cortés, and the great-granddaughter of Aztec Emperor Moctezuma II.

Florida Current: The Florida Current is a thermal ocean current that flows from the Straits of Florida around the Florida Peninsula and along the southeastern coast of the United States before joining the Gulf Stream Current near Cape Hatteras.  Its contributing currents are the Loop Current and the Antilles Current.  The current was discovered by Spanish explorer Juan Ponce de León in 1513.

Diego Fernández de Proaño: Diego Fernández de Proaño was a Spanish explorer and conquistador who served with Nuño Beltrán de Guzmán in the exploration of New Galicia.  He was named Justice Major of the city of San Miguel de Culiacán by Guzmán and was later accused of abusing his power to enslave hundreds of local indigenous inhabitants in direct violation of orders from the newly established province's governor.  He was the son of Juan de Proaño and of Ana de Cervantes.

USS Tortuga (LSD-26): USS "Tortuga" (LSD-26) was a "Casa Grande"-class dock landing ship in the United States Navy.  She was the first Navy ship to be named for the Dry Tortugas, a group of desert coral islets 60 miles west of Key West, Florida, which were discovered in 1513 by Spanish explorer Ponce de Leon.

Juan Ponce de León: Juan Ponce de León (] ; 1474 – July 1521) was a Spanish explorer and "conquistador".  He became the first Governor of Puerto Rico by appointment of the Spanish crown.  He led the first known European expedition to "La Florida", which he named during his first voyage to the area in 1513.  Though in popular culture, he was supposedly searching for the Fountain of Youth, there is no contemporary evidence to support the story, which is likely a myth.

Vasco Núñez de Balboa: Vasco Núñez de Balboa (c. 1475around January 12–21, 1519) was a Spanish explorer, governor, and conquistador.  He is best known for having crossed the Isthmus of Panama to the Pacific Ocean in 1513, becoming the first European to lead an expedition to have seen or reached the Pacific from the New World.

Supporting paragraphs: History of the Panama Canal Vasco Núñez de Balboa
Answer: isthmus