Kendrapada: A couple died after their car skidded off NH-53 and plunged into a deep, water-filled excavation pit at Gadagaon village under Paradip Lock police station in Jagatsinghpur district around midnight on Tuesday.The deceased were identified as Bibhuti Bhusan Das (60) and his wife, Pratima Das (58). Bibhuti was working as an engineer in marine department of Paradip Port and retired from service on Aug 31.According to police, the couple was returning to their home in Paradip in their car from one of their relatives’ houses at Nimidi village when the vehicle hit a road divider. Bibhuti reportedly lost control of the car, which veered off the highway and plunged into the water-filled pit.Preliminary investigation suggest that both died of asphyxiation after remaining trapped underwater for several hours in the night. Police retrieved the bodies and sent them to Biju Patnaik Memorial Hospital in Paradip for autopsy, said IIC of Paradip Lock police station Rashmi Ranjan Das.