The Great Whale in the Bosphorus - the story of Porphyrios
- Martin
- 1 day ago
- 2 min read
In the 6th century, the sea route through the Bosphorus was at times considered dangerous. Contemporary sources tell of a large sea creature, a so-called kētos, that for years struck ships and caused unease among sailors in Constantinople.
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The story is known from Procopius, who lived under Justinian I and described these events as part of his own time. He operated close to power and later wrote the notorious work Secret History, in which Theodora in particular was subjected to unusually harsh criticism, at times expressed in openly coarse and even obscene terms.
He described a massive sea creature moving through the Bosphorus and the Sea of Marmara over an extended period. It was given the name Porphyrios. According to the account, this was not a single incident but something that recurred over the years.
Ships were struck. Sometimes with enough force to cause serious damage. At other times, crews escaped with little more than fear. The key point was not the details of individual encounters, but that it kept happening.
At the time, the Bosphorus was a lifeline for the city. Transport, trade and communication largely depended on the water. When uncertainty arose here, it had a direct impact on everyday life.
Procopius described how sailors began to take the situation into account. Routes were adjusted, and certain areas were avoided when possible. A persistent sense of risk became attached to sailing these waters.
Attempts were made to capture or kill the creature, but without success. It disappeared and later reappeared. In that way, it remained a recurring presence in the city over a longer period.
The story does not end with a dramatic confrontation. According to the sources, the animal eventually washed ashore and was killed by locals.
Today, researchers suggest it was most likely a large whale that had entered waters where it did not normally belong.
That does not change what it must have been like to set out on the Bosphorus at the time. Not as a single dramatic event, but as an ongoing uncertainty that followed you out onto the water.
Image note: The illustration at the top of the article is based on a photo taken from a ferry on the Bosphorus in 2026 and has been adapted with the help of artificial intelligence to match the story told here.
