The rāhui (temporary closure) covers the coastline from Taieri Mouth, south to Bull Creek and Glenledi, Te Rūnanga o Ōtākou manager Nadia Wesley-Smith said.
The closure would lift at 11pm tomorrow.
A police spokeswoman said a body was located in a cave at Taieri Mouth at about 11pm yesterday.
"The death is currently being treated as unexplained and inquiries are underway to determine what has occurred," the spokeswoman said.