The unnamed project manager, in his 30s, was taking an early morning stroll along Tan-y-Bwlch beach near Aberystwyth when he stumbled across the find on the beach.
He saw around 30 black packages tied with rope to empty jerry cans designed to keep the Class A drugs afloat at sea.
The walker told the Mail on Sunday: “I was out for my early morning walk when I saw something on the beach.
“I was intrigued and walked up to it and knew what it was almost straight away. An old lady called the police and they came around half an hour later.
“They cut open a bag and it looked like pure cocaine. They dragged it off the beach and took it away.”
A spokeswoman for Dyfed-Powys Police said: “We are investigating the discovery of a significant quantity of what is thought to be cocaine, spotted along the Ceredigion coast this weekend.
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“Enquiries are being undertaken to establish how such an unusually large amount of the controlled drug came to wash up on the Welsh shore, following recent storms.
“The precise quantity is still being established and at this time no-one has been arrested in relation to this matter.
“Officers have thanked those who found the packages and their sensible actions in reporting the matter immediately.”
Last month more than a dozen bricks emblazoned with a ‘Dior’ label washed ashore in the town of Biloxi, a city that sits on the Gulf of Mexico.
Mississippi Bureau of Narcotics Director Steven Maxwell said of that haul: "There was likely to be a large amount of drugs that either fell off a vessel or they were intentionally dropped off to be picked up by someone else or another group of individuals.”
One man was arrested for allegedly trying to remove one of the packages.