Whale oil is the refined oil that is harvested from whales, and the basis of the Empire's industrial revolution. Highly volatile, it is held in tanks which can be found throughout major cities. In Dunwall, it is used to power all technology, while in Karnaca, it is used interchangeably with wind power.
Whale oil's potential as an energy source was discovered by the natural philosopher Esmond Roseburrow, who observed vagabonds in Slaughterhouse Row using collected whale oil to stoke fires. Through a special refinement process, he turned whale oil into a fuel source that advanced the Isles' technology by centuries. It also turned the once marginal and supplementary whaling industry into the most vital industry for all the Isles. Whaling houses like the Greaves Company and the Rothwild Slaughterhouse turned into wealthy, industrial powerhouses. Later, Anton Sokolov proposed the first plans to use whale oil in technological weaponization in the early 1800s.
By 1852, whales had become increasingly rare due to overfishing. Empress Emily Kaldwin issued an unpopular decree ordering the rationing of whale oil across the Empire to mitigate shortages, which resulted in driving its price up and hampering its availability to people outside of industry, aristocracy, and government. While some began to speculate that the Empire's age of industry would end once whale oil finally disappeared, commentators in Karnaca noted that the city had a ready and abundant alternative power source in the form of the local wind currents.
Whale oil is easily recognized by the bright blue glow it emits, which can be best seen in the whale processing and oil refining areas of the Greaves Refinery in the Flooded District and in Slaughterhouse Row, where leaked whale oil illuminates the halls and surrounding streets. It is extremely unstable and volatile; throwing or shooting a full whale oil tank will cause it to explode.
It is speculated that whale oil is naturally produced within the bodies of whales due to great pressures deep in the ocean, for the purpose of temperature regulation. It is theorized by Piero Joplin that if the human body were exposed to such pressures, it could produce something similar to whale oil; these experiments have not come to fruition, due to financial and ethical concerns.
- The in-universe whale oil is likely based on the real-life substance called "spermaceti", found in and chiefly harvested from sperm whales. Like the oil, spermaceti was harvested by 18th century whalers and refined to be used as fuel in lamps, heaters and candles. As the whales of Dishonored closely resembles sperm whales, the design choice is appropriate.