Aboard a ship, on the ocean, as in Within a few hours the ship would be out at sea. During World War II a famous American newscaster addressed his radio broadcasts to listeners everywhere, including “all the ships at sea.” [1300s]
Also, all at sea. Perplexed, bewildered, as in She was all at sea in these new surroundings. This idiom transfers the condition of a vessel that has lost its bearings to the human mind. Charles Dickens used it in Little Dorrit (1855): “Mrs. Tickit ... was so plainly at sea on this part of the case.” [Second half of 1700s]
Words nearby at sea
How to use at sea in a sentence
At the end of 1652 Deane returned to his command as general-at-sea, where Monck had succeeded Popham, who had died in 1651.
He was still ill, and found himself growing daily worse, but he made an effort to aid his brother generals-at-sea.A Short History of the Royal Navy 1217 to 1688|David Hannay
A moment's rustling pause in the darkness down below, and then the far-out-at-sea voice spoke again.