The term 'HUGE EXPANSE' can be broken down into two crossword solutions: SEA (3 letters) and HUGE (4 letters). The solution SEA is a body of salt water that covers most of the Earth's surface, and is divided into four major oceans: the Pacific, Atlantic, Indian, and Arctic. The solution HUGE is an adjective meaning very large in size or amount. Therefore, the term 'HUGE EXPANSE' can be interpreted as a very large area of ocean.