True. The Pacific Ocean covers approximately 63.8 million square miles (165.25 million km²), which is about 32% of Earth's total surface area. The Mariana Trench reaches a maximum known depth of about 36,070 feet (10,994 meters) at the Challenger Deep. The ocean was named by Portuguese explorer Ferdinand Magellan.

True. The International Hydrographic Organization (IHO) officially recognized the Southern Ocean in 2000, though debates continue. It encircles Antarctica from the coastline to 60°S latitude. Its defining feature is the Antarctic Circumpolar Current, the world's largest ocean current, flowing clockwise around the continent.

False. The Dead Sea is not a sea but a hypersaline lake. It is landlocked between Israel, Jordan, and Palestine. It has no outlet to any ocean. Its name comes from the fact that its extreme salinity (about 34%, nearly 10 times saltier than ordinary seawater) prevents aquatic life from thriving.

True. The Sargasso Sea is located in the North Atlantic Ocean and is bounded by four currents: the Gulf Stream, North Atlantic Current, Canary Current, and North Equatorial Current. It is named after Sargassum, a brown seaweed that accumulates there, creating a unique floating ecosystem.

True. The Arctic Ocean covers about 5.4 million square miles (14 million km²), about 1.5 times the size of the United States. Its average depth is approximately 3,406 feet (1,038 meters). Summer sea ice extent has declined by about 13% per decade since satellite records began in 1979.

True. Between about 5.96 and 5.33 million years ago, the Mediterranean Sea was cut off from the Atlantic Ocean and largely evaporated, leaving thick salt deposits (the Messinian Salinity Crisis). It was then refilled by the Zanclean flood, one of Earth's largest known floods.

True. The Indian Ocean has the highest surface water temperatures among the five oceans, typically 22-28°C (72-82°F). It accounts for about 20% of the world's water surface. The Strait of Malacca, between Malaysia and Indonesia, is one of the world's busiest shipping channels, carrying about 25% of global trade.

True. The Caspian Sea covers about 143,000 square miles (371,000 km²), making it the largest inland body of water. It is bordered by five countries: Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan. Its salinity is about 1.2% (compared to ocean average of 3.5%), derived from ancient ocean remnants.

True. The Red Sea's name likely comes from Trichodesmium erythraeum, a cyanobacterium that can turn the water reddish-brown when it blooms. It has salinity of about 4% (compared to 3.5% global average) and temperatures can reach 30°C (86°F) at the surface. It separates Africa from the Arabian Peninsula.

False. The Gulf of Mexico is a marginal sea (or gulf) of the Atlantic Ocean, not an ocean itself. Its average depth is about 1,615 meters (5,299 feet), with a maximum depth of about 4,384 meters (14,383 feet) in the Sigsbee Deep. It is partially landlocked by Mexico, the United States, and Cuba.