A Bridlington car park was cordoned off by Humberside Police yesterday.
An injured man was found in the harbour car park off South Cliff Road at around 9am on Thursday September 12.
He was taken to hospital for treatment "what are thought to be serious injuries."
Officers are conducting enquiries "to establish how he came to be injured" and will be in the area today.
A spokesperson from Humberside Police said: "We do believe that the man was on Bridge Street until around 1.40am and we are keen to hear from anyone that saw him in the area throughout the night.
"We ask anyone with any information to call our non-emergency 101 line quoting log 121 of 12/09/18 or Crimestoppers anonymously on 0800 555 111."