gunwales
Gunwale is far from unique in modern English language in having an accepted, traditional (notice I did not say "right" or "correct") pronunciation that is not obvious from its spelling. The term comes from the days of sailing warships -- a gun is a gun, and a wale is a ridge (as in wide- or narrow-wale corduroy), comes from the Old English "walu" through the Middle (and modern) English "weal," a ridge resulting from a skin injury, and has nothing to do with cetaceous mammals. The term originally described the piece of wood added to the exterior of a hull above the gun deck to give stiffness and strength, needed in that location especially because of the weakening holes in the hull made by the gun ports, and the new holes in the hull at the level of the gun decks that would result from a close-in engagement with another warship.
Other maritime examples of words not pronounced as spelled include forecastle, boatswain, leeward, bowline, mainsail, and topgallant.
Non-maritime examples of words with spelling only loosely connected to traditional pronunciation (if connected at all) are to numerous to count, and include, e.g., height, through, enough, schism, and breeches (and for our linguistically fearless president, nuclear).
Those wanting to change spelling to match pronunciation are in good, but generally unsuccessful company; George Bernard Shaw went so far as to invent new alphabet for English -- Shavian -- which was not a wild success, to say the least, and I believe that the style manual of Chicago Tribune favors some pronunciation spellings (or at least did once upon a time). Some spellings that have been shortened to reflect pronunciation have become accepted informally, such as "thru" -- but shortening words can create its own issues by not giving any clue to pronunciation -- LOL, SWMBO.
Sometimes alternate words are available -- in the world of canoes, gunwales are often (raise you hand if you do not pronounce the "t" in often) referred to as "rails."
Such is the English language, which even with its quirks, idiosyncracies, and difficult spellings/pronunciations, has today become the lingua franca of most of the modern world.