The small male pilot whale was found barely alive in a canal near the border with Malaysia, Thailand’s Department of Marine and Coastal Resources said.
It vomited up five bags while rescuers used buoys to keep it afloat in a rescue attempt, while an umbrella was held to protect it from the blazing sun.
A veterinary team tried “to help stabilise its illness” but the whale later died on Friday afternoon, officials said.
An autopsy revealed 80 plastic bags weighing up to eight kilograms (18 pounds) in the creature’s stomach.
Thon Thamrongnawasawat, a marine biologist and lecturer at Kasetsart University, said the bags had made it impossible for the whale to eat any nutritional food.
“If you have 80 plastic bags in your stomach, you die,” he said.
Mr Thamrongnawasawat added that at least 300 marine animals, including pilot whales, sea turtles and dolphins, perish each year in Thai waters after ingesting plastic.
He said: “It’s a huge problem. We use a lot of plastic.”
The pilot whale’s plight generated sympathy and anger among Thai citizens.
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One Twitter user wrote: “I feel sorry for the animal that didn’t do anything wrong but has to bear the brunt of human actions.”
:: Sky’s Ocean Rescue campaign encourages people to reduce their single-use plastics. You can find out more about the campaign and how to get involved at www.skyoceanrescue.com