A 33-year-old man jumped into the Arabian Sea from Mumbai's Bandra-Worli Sea Link in the early hours of Thursday, triggering a search, an official said.
The operation to trace him is being carried out by the Mumbai police and fire brigade with the help of the Indian Navy and Coast Guard, the official said.
The incident took place around 4 am when Vinay Yadav, a resident of Jogeshwari in the western suburbs, jumped into the sea from the cable-stayed bridge.
Yadav, a driver by profession, came in an Innova car, parked it on the bridge and jumped into the sea, he said.
The local police and fire brigade began a search. As they faced difficulties, the Indian Coast Guard and Navy were roped in, the official said.
The reason behind Yadav's decision to plunge into the sea is not yet known, he added.
On July 31, a 57-year-old man jumped from the sea link, triggering a search by the Navy and Coast Guard. His body was recovered the next day.