Windows in a seafront shelter on the Esplanade were damaged in Seaford on Sunday December 28.
Sussex Police were alerted about the damage at about 9.30pm the same day.
A group of two or three boys were seen in the area at the time and enquiries are continuing.
No arrests have been made.
The beach shelter was one of a number of measures taken to improve the seafront by Seaford Town Council last summer.
It also installed larger litter bins, helped to reopen kittiwake colony and beauty spot Splash Point and refurbished the shelter.
The shelter was vandalised in February and the majority of the glass panels were smashed.
Anyone with information is asked to email email@example.com or call 101 quoting serial 1217 of 28/12.