Police said the man from Kantale, a town in eastern Sri Lanka, had asked his family to bury him for an attempt to get in the record books, the Lankapuvath news agency reported.
The man, identified as a member of the Sri Lankan civil defense force, was buried Saturday morning.
When family members opened the trench at 4 p.m. the same day as they had been told, they found the man unconscious, the report said.
He was taken to a hospital where he was pronounced dead, police said.
Police were investigating the incident, the news agency said.