The new Wagamama restaurant on the site of the former harbourmaster's office on the Brayford has been forced to close until further notice due to flood water.
The restaurant itself has avoided the rising water levels but access to the restaurant has been cut off.
Wagamama manager Danny Johnson said: "Inside we are fine but the access is the problem.
"Until the water is cleared and we can get people in and out safely we can't open.
"We have tried a few ways of clearing the water but we are going to have to wait until the drains become useful again and the water subsides."
It is hoped the restaurant could reopen this evening.