9-letter name for an area of 10 million square miles–4/5 the size of africa–but only about 120,000 square miles of it is dry land

Polynesia Should be the correct answer, hope this helps.

Explanation:

places of higher salinity. there are parts of the ocean where hardly any rain falls but warm dry winds cause lots of evaporation. this evaporation removes water – when water vapour rises into the atmosphere, it leaves the salt behind, so the salinity of the seawater increases. this causes the seawater to become denser.