Qwghlm is a fictional archipelago, comprising the two large islands of Inner and Outer Qwghlm and a number of small uninhabited outcroppings. Qwghlm is said to somewhat resemble islands of the Outer Hebrides, probably combining aspects of Skye and Uist. It is from where Eliza was originally kidnapped. In the Baroque Cycle it is claimed by both England and France, known as "The Duchy of Arcachon-Qwghlm", which is why both Louis XIV and William of Orange grant Eliza titles. The language of Qwghlm is used in Cryptonomicon by the British in much the same way that the Navajo language was used by the Americans.
Qwghlm's primary indigenous life forms, aside from various seabirds valued for their guano, are the skrrgh (a small rodentlike creature) and the Qwghlmian sheep, an evolutionarily enhanced creature known for the distinctive texture of its wool.
According to the audiobook versions of The Baroque Cycle and Cryptonomicon, in the late 17th century "Qwghlm" was pronounced "Taghum", with stress on the second syllable. By the mid-20th century, the pronunciation had altered to something closer to "Tagh'm", with the first syllable emphasized and the second vowel almost elided.