Green’s Dictionary of Slang

1. (also the big pond, the fish-pond) the ocean esp. the Atlantic Ocean.

1780		Royal Gaz. (N.Y.) 22 Jan. n.p.: Then Jack was sent across the Pond To take her in the rear, Sir [DAE].
1844		Leeds Times 22 June 6/1: ‘I’d much rather stay / At home to gather glory, than adventure / Across the great fish-pond to study Botany.‘ [...] ‘Is that Botany Bay thou’rt speakin’ on?’.
1846		Swell’s Night Guide 64: Swore – he, the deed had stagg’d. So queer’d Bill’s council, and got Billy lagged. / He crossed the fish-pond, for his natural life.
1848		‘Ned Buntline’ Mysteries and Miseries of N.Y. II 64: We want to make one or two large hauls; lifts that will make folks stare more than they ever have on this side of the big fish-pond.
1854		N.Y. Clipper 4 Feb. 3/3: When to ‘catch a match with some of the fancy on this side of the big pond’ .
1859		Matsell Vocabulum 69: Pond The Ocean.
1864, 1867, 1870		Hotten Sl. Dict. 204: Pond, or herring-pond the sea; so called by those who were sent across it as the national expense.
1882		Bristol Magpie 26 Oct. 9/2: Latest advices, from ‘across the pond,’ show, that the Yanks are ‘parting’ extraordinarily freely over the coming [Lily] Langtry performances.
1882		Nat. Police Gaz. (NY) 7 Oct. 3/3: [T]he burlesque troupes and the dramatic artists are on their way across the big pond and back.
1888		Sheffield Eve. Teleg. 25 Jan. 4/4: Sir Morell has just refused a nice little doucer on 30,000 dollars, which was offered to him if he would run across the ‘mill-pond’ to see one of the inumerable ‘leading citizens’ in the Staes .
1890		Sporting Times 12 Apr. 7/1: I have tried to induce him to stay here the rest of his natural life just as a pattern of what we can do on the other side of the pond.
1895		C. Crowe Aus. Sl. Dict. 60: Pond (or Herring Pond), the ocean.
1903		J. Conrad Typhoon 200: Oh! It was pretty complete, I can tell you; and you may run to and fro across the Pond to the end of time before you find yourself with such a job on your hands.
1914		C. Holme Lonely Plough (1931) 106: Over the pond I ran up against a queer sort of lie-slinger.
1918		R. Lardner Treat ’Em Rough 58: Some of the boys laughed at me tonight when I told them about going to attend the lessons but I will be the one that does the laughing when we get across that old pond.
1920		Eve. Teleg. 2 June 3/4: ‘Europeans are all very well,’ said a visitor from across the pond, ’but I tell you that we Americans are the goods’.
1928		M.C. Sharpe Chicago May (1929) 14: Mine was a slow steamer. It took ten days to cross the pond.
1928		Western Dly Press 19 Mar. 4/6: [headline] Cunard Comfort Crossing ‘The Pond’.
1931		Sheffield Indep. 2 June 4/5: The Frenchman is is to be seen in [the film] ‘The Big Pond’.
1933		(con. 1900s) F. Riesenberg Log of the Sea 120: All the fine old girls who pounded across the pond in 1899 are gone. [...] The skippers are, for the most part, gone with their ships.
1955		B. Appel Tough Guy [ebook] ‘It’s a big pond, mister. I remember when I crossed it in a troop ship, a big pond’.
1968		‘Hy Lit’ Hy Lit’s Unbelievable Dict. of Hip Words 1: across the pond – Across the ocean; to the flipside of the world.
1975		L. Bangs in Psychotic Reactions (1988) 169: Who else would doze his way back over the pond in a giant secobarbital capsule and labor for months [...] to puke up Berlin.
1999		Guardian Guide 14–20 Aug. 39: Some of the top American wags currently playing this side of the pond.
2008		Camden New Journal (London) Rev. 4 Sept. VII: Sumptuous costumes and wonderful locations mean this film will no doubt be a [...] hit across the Pond. But as a drama its a stinker.

2. the English Channel.

1921

N&Q 12 Ser. IX 347: Pond (The). The English Channel.

3. (US) the Pacific Ocean.

1965

H. Rhodes Chosen Few (1966) 17: I was up at Earl myself before I went across the pond.

4. (N.Z.) the Tasman Sea.

1912		Truth (Wellington) 6 Apr. 6/1: The idea was to see McGregor off to invercargill by train, and then to cross the pond to Fisher’s continent.
2003		McGill Reed Dict. of N.Z. Sl.