Vasco Núñez de Balboa in the context of "Explorer"

Today the term South Seas, or South Sea, most commonly refers to the portion of the Pacific Ocean south of the equator. The term South Sea may also be used synonymously for Oceania, or even more narrowly for Polynesia or the Polynesian Triangle, an area bounded by the Hawaiian Islands, New Zealand and Easter Island. Pacific Islanders are commonly referred to as South Sea Islanders, particularly in Australia.

The term was coined as Mar de Sur, or "South Sea",  by Spanish conquistador Vasco Núñez de Balboa in 1513 as he it encountered on the southern coast of the Isthmus of Panama and it was applied to the entirety today's Pacific Ocean. In 1520, Ferdinand Magellan named the same ocean the Pacific Ocean, and over time Magellan's name became more well-known.

Francisco Pizarro (/pɪˈzɑːroʊ/; Spanish: [fɾanˈθisko piˈθaro]; c. 16 March 1478 – 26 June 1541) was a Spanish conquistador, best known for his expeditions that led to the Spanish conquest of the Inca Empire.

Born in Trujillo, Spain, to a poor family, Pizarro chose to pursue fortune and adventure in the New World. He went to the Gulf of Urabá and accompanied Vasco Núñez de Balboa in his crossing of the Isthmus of Panama, where they became the first Europeans to see the Pacific Ocean from the Americas. He served as mayor of the newly founded Panama City for a few years and undertook two failed expeditions to Peru. In 1529, Pizarro obtained permission from the Spanish crown to lead a campaign to conquer Peru and went on his third, and successful, expedition.

The Darien scheme was an unsuccessful attempt, backed largely by investors of the Kingdom of Scotland, to gain wealth and influence by establishing New Caledonia or Britain-in-Panama, a colony in the Darién Gap on the territory of present-day Panama, in the late 1690s. The plan was for the colony, located on the Gulf of Darién, to establish and manage an overland route to connect the Pacific and Atlantic Oceans. The backers knew that the first sighting of the Pacific Ocean by Vasco Núñez de Balboa was after crossing the isthmus through Darién. The expedition also claimed sovereignty over "Crab Isle" (modern day Vieques, Puerto Rico) in 1698, yet sovereignty was short-lived. The settlement attempt failed; more than 80 percent of participants died within a year, and the settlement was abandoned twice.

There are many potential explanations for the disaster, including poor planning and provisioning; divided leadership; a lack of trade with local indigenous tribes or neighbouring Dutch and English colonies; epidemics of tropical disease; widespread opposition to the scheme from commercial interests in England; and a failure to anticipate a military response from the Spanish Empire. The settlement was abandoned in March 1700 after a siege by Spanish forces that also blockaded the harbour.

Explorers are listed below with their common names, countries of origin (modern and former), centuries of activity and main areas of exploration.

The Spanish conquest of New Granada refers to the conquest between 1525 and 1540 by the Spanish monarchy of the Chibchan-speaking nations of modern-day Colombia and Panama, mainly the Muisca and Tairona that inhabited present-day Colombia, beginning the Spanish colonization of the Americas. It is estimated that around 5.25 million people died as a result of Spanish Conquest, either by disease or direct conflict. This represents 87.5% of the Pre-Columbian population of Colombia.

In 1513 the Spanish conquistador Vasco Núñez de Balboa first crossed the Isthmus of Panama. When the narrow nature of the Isthmus became generally known, European powers noticed the possibility to dig a water passage between the Atlantic and Pacific Oceans.

A number of proposals for a ship canal across Central America were made between the sixteenth and nineteenth centuries. The chief rival to Panama was a canal through Nicaragua.

Santa María la Antigua del Darién—rendered as Dariena in the Latin of De Orbe Novo—was a Spanish colonial town founded in 1510 by Vasco Núñez de Balboa. Located in present-day Colombia approximately 40 miles (64 km) south of Acandí, within the municipality of Unguía in the Chocó Department, it was the first permanent European settlement on the mainland of the Americas and served as the first capital of Castilla del Oro. The settlement was abandoned in 1524 after the capital was transferred to the newly founded Panama City and was subsequently attacked and burned by indigenous peoples.

During the Age of Discovery, the Spanish Empire undertook several expeditions to the Pacific Northwest of North America. Spanish claims to the region date to the papal bull of 1493, and the Treaty of Tordesillas signed in 1494. In 1513, this claim was reinforced by Spanish explorer Vasco Núñez de Balboa, the first European to sight the Pacific Ocean, when he claimed all lands adjoining this ocean for the Spanish Crown. Spain only started to colonize the claimed territory north of present-day Mexico in the 18th century, when it settled the northern coast of Las Californias.

Starting in the mid-18th century, Spain's claims in the Pacific Northwest began to be contested by the British and Russians, who established fur trading posts and other settlements in the region. King Charles III of Spain and his successors sent several expeditions from New Spain to present-day Canada and Alaska between 1774 and 1793 to strengthen the Spanish claims. These efforts would eventually come to naught when Spanish claims in the region were ceded to the American government in the 1819 Adams–Onís Treaty.