What is the only sea on Earth that has no coastline, being entirely defined by ocean currents? This sea is located in the North Atlantic Ocean, bounded by four ocean currents: the Gulf Stream to the west, the North Atlantic Current to the north, the Canary Current to the east, and the North Equatorial Current to the south. The sea covers about 2 million square kilometers (772,000 square miles). Its boundaries shift with the currents, so it has no fixed coastline. The sea is famous for the Sargassum seaweed that floats on its surface (giving it a brownish color) and for being a spawning ground for European eels and American eels. The sea was named by Portuguese sailors who compared the floating seaweed to a thicket (sargaço in Portuguese). The sea is also known for the Bermuda Triangle – the region where many ships and planes have mysteriously disappeared, though scientists attribute this to human error, piracy, and weather. The sea has very little wind, making it a "calm zone" where sailing ships could be stranded for weeks.

What is the largest country (by land area) that has no permanent rivers? This country is an archipelago of 33 atolls and reef islands in the Pacific Ocean, with a total land area of 26,000 square kilometers (10,000 square miles). It has no rivers because its coral islands are too porous to retain surface water. The country relies entirely on rainwater and desalination for fresh water. The country's maximum elevation is only 5 meters (16 feet) above sea level, making it extremely vulnerable to climate change. The country has a population of about 100,000 people. The capital is Funafuti. The country was formerly called the Ellice Islands (British colony). The country gained independence in 1978. The country's economy depends on fishing and remittances from Tuvaluans working abroad (especially in New Zealand and Australia). The country's internet domain (.tv) generates significant revenue (sold to a California company for $50 million over 12 years). The country has no military. The country has been inhabited for about 3,000 years.

What is the only country that lies entirely within another country (an enclave)? This country is the smallest independent state in the world by both area (0.44 square km / 0.17 square miles) and population (about 800 people). It is completely surrounded by the city of Rome, Italy. The country is the spiritual and administrative center of the Roman Catholic Church, ruled by the Pope (elected for life by the College of Cardinals). The country has its own postal service (issuing its own stamps), its own currency (the Euro, under a special agreement with Italy), its own flag (yellow and white with crossed keys), its own newspaper (L'Osservatore Romano), its own radio station, and its own railway station (the shortest railway in the world, only 300 meters long). The country has no taxation, no army (the Swiss Guard, 135 soldiers, serves as the Pope's bodyguard but is not an army of the country itself), and no prison (criminals are held in Italian prisons). The country became independent in 1929 under the Lateran Treaty.

What is the world's largest sand island (composed entirely of sand), located off the coast of Australia? This island is 122 km (76 miles) long and 15 km (9 miles) wide, covering an area of 1,840 square km (710 square miles). It is a UNESCO World Heritage site. Despite being made entirely of sand, the island supports rainforests (trees growing on sand), over 100 freshwater lakes (some of the clearest in the world), and 40 perched dune lakes (lakes that form in depressions between sand dunes). The island has over 230 bird species. The island is famous for its purebred dingo population (the most pure in Australia). The island's sand is 98% silica quartz, so white it looks like snow. The island's lakes are so pure that swimming in them can condition hair (the silica acts as a natural conditioner). The island's traditional owners are the Butchulla people, who have lived there for over 5,000 years. The island was formerly called by a European name, but the official name was changed back to its Aboriginal name in 2002. The island's name means "paradise" in the Butchulla language.

What is the only country in the world that has no official capital city (no constitutionally designated capital)? This country is a city-state with no formal capital – the entire country is a single municipality. The country's government is based in the area of Ngerulmud (since 2006), but the constitution does not designate Ngerulmud as a formal capital. The previous capital was Koror. The country has a population of 18,000 people, making it the third smallest country in the world (after Vatican City and Monaco). The country is a Pacific island nation with 340 islands. The country is famous for its "rock islands" (445 uninhabited limestone islands), which are a UNESCO World Heritage site. The country is also famous for Jellyfish Lake (one of only a few marine lakes where jellyfish have evolved to be stingless). The country uses the US Dollar as its currency. The country is one of the youngest countries in the world, becoming independent in 1994 (after being part of the US-administered Trust Territory of the Pacific Islands). The country's name comes from the Palauan word "beluu" (village).

What is the longest mountain range in the world above water? This mountain range extends for 7,000 km (4,350 miles) along the western edge of South America, from Venezuela in the north to Tierra del Fuego in the south. The range passes through seven countries: Venezuela, Colombia, Ecuador, Peru, Bolivia, Argentina, and Chile. The range includes the highest peak outside Asia: Aconcagua (6,961 m / 22,838 ft) in Argentina. The range is the world's highest mountain range outside Asia. The range was formed by the subduction of the Nazca Plate beneath the South American Plate. The range is volcanically active, with over 30 active volcanoes. The range contains the world's highest capital city (La Paz, Bolivia, at 3,650 m), the world's highest navigable lake (Lake Titicaca, 3,812 m), and the world's largest salt flat (Salar de Uyuni, Bolivia, 10,582 sq km). The range is also home to the Llullaillaco (6,739 m), the world's highest archaeological site (Inca mummies found frozen). The range's name comes from the Quechua word "anti" (east).

What is the most remote inhabited island in the world (farthest from any other human settlement)? This island is located in the South Atlantic Ocean, 2,400 km (1,500 miles) from the nearest inhabited land (Saint Helena) and 2,800 km from South Africa. The island has a population of about 250 people. The island was discovered in 1506 by Portuguese explorer Tristão da Cunha. The island is volcanic, with an active volcano (Queen Mary's Peak, 2,062 m). The island has no airport – access is only by a 7-day boat trip from South Africa. The island has a unique ecosystem, with dozens of endemic species found nowhere else. The island's only settlement is Edinburgh of the Seven Seas (also called "The Settlement"). The island has no crime, no hotels, no restaurants, and no airport. The island's economy is based on fishing (crayfish), farming, and selling stamps. The island has its own internet domain (.ac). The island is a British Overseas Territory. The island was used as a secret listening post during the Cold War. The island has one pub (the Albatross Bar) and one school (with about 15 students).

What is the only sea on Earth that has no tides (almost no tidal variation)? This sea is located in southern Europe, almost completely surrounded by land (connected to the Atlantic Ocean only through the narrow Strait of Gibraltar, 14 km wide). Because the strait is so narrow, the tidal movement from the Atlantic is very small – tides in this sea rarely exceed 0.5 meters (20 inches), compared to the Atlantic where tides can be 5-15 meters (16-50 feet). Some scientists call this sea "non-tidal" because the tidal range is so small it is almost unnoticeable. The sea covers 2.5 million square km (970,000 square miles). The sea has 33,000 km of coastline. The sea's average depth is 1,500 meters (4,900 feet). The sea's water is very salty (38-39 parts per thousand) because evaporation exceeds freshwater inflow. The sea has 5,000+ islands (including Cyprus, Crete, Sicily, Sardinia, Corsica, Malta, the Balearics). The sea is the birthplace of Western civilization (Greek and Roman empires). The sea is one of the most polluted in the world due to heavy shipping traffic and coastal development.

What is the only country whose national flag is not a quadrilateral (rectangular or square) but has a unique shape? This country's flag is a double-pennon (two triangles stacked). The flag is crimson red with a blue border and a white stylized sun and moon. The flag's shape is a combination of two separate triangular pennons used by rival branches of the country's royal family, which were combined when the country unified. The flag symbolizes the country's Himalaya mountains (the triangles represent the mountains) and the two major religions (Hinduism and Buddhism). The country is the only country that has never been colonized (never lost its independence). The country has no formal constitution (until 2008, it was an absolute monarchy). The country's capital is Kathmandu. The country is home to Mount Everest, the world's highest peak. The country's flag was adopted in 1962. The flag's ratio is not fixed, but the standard is about 5:4. The flag is the only national flag that is not rectangular or square. The country's name means "Land of the Himalayas" in Sanskrit.

What is the largest desert in the world by area (a cold desert, not a hot sand desert)? This desert is the coldest, driest, and windiest continent on Earth. It covers 14.2 million square km (5.5 million square miles) – larger than Europe. A desert is defined by precipitation, not by sand or heat. This desert receives less than 50 mm (2 inches) of precipitation annually (mostly as snow). It contains 90% of the world's ice and 70% of its fresh water. The desert has no permanent human population. The coldest temperature ever recorded (-89.2°C / -128.6°F) occurred here. The desert has "dry valleys" that have had no rain for 2 million years (the driest places on Earth). The desert is governed by the Antarctic Treaty, which designates it for peaceful scientific research. The desert is home to about 5,000 seasonal researchers in summer and 1,000 in winter. The desert has only two flowering plant species (Antarctic hair grass and Antarctic pearlwort). The desert's ice sheet is up to 4.8 km (3 miles) thick. If the ice sheet melted, global sea levels would rise by 58 meters (190 feet).