"Almost all readers are content to interpret Qwghlm as a wholly fictitious and fanciful invention, which is correct. From time to time someone will get it into their head that it is a veiled description of some real place, and so let me just state here flat-out that it is not meant that way at all. It is made-up."
-- Neal Stephenson

The islands of Inner Qwghlm and Outer Qwghlm and surrounding outcroppings situated off the northwestern coast of Britain, as well as the nation located thereon, were created by author Neal Stephenson for Cryptonomicon, published in 1999. Depicted as a British territory located somewhere in the North Atlantic, Qwghlm is notable for its unique and nearly unpronounceable language, Qwghlmian, featuring an alphabet consisting entirely of triangles with no vowels. (Its 16 consonants being convenient for rendering in a four-digit binary code.) The language as described in Quicksilver is so pithy that a 30,000-character letter in Qwghlmian is a 40,000-word book when translated into Latin. Each island has its own distinct dialect.

Qwghlm serves as a backdrop for various elements of Cryptonomicon's plot, including its role in history, such as piracy and espionage, which are explored further in Quicksilver. The islands are said to have a rich and convoluted past, with references to their involvement in cryptography, smuggling, and other clandestine activities.

It's worth noding that Qwghlm has also been referenced in other works by Neal Stephenson, as well as in discussions about constructed languages and fictional world-building. As for pronunciation? The author says:

"English people who attempt to duplicate this frequently come out with something that sounds like TAG'em. Though this really does not sound anything like the correct pronunciation, Qwghlmians who hear it from the mouth of an Englishman will usually understand…and more or less hide their disdain."

More of Neal's words in re.