Eight teenagers have been arrested on suspicion of breaking into and burgling the Weymouth Sea Life Centre.
A wooden shutter was forced open and sweets and drinks were stolen from the tourist attraction.
Officers were called on Wednesday after a group of children were seen inside the building just after 2200 BST.
Six boys, five aged 15 and one aged 16, and two girls, aged 13 and 16, were arrested on suspicion of burglary and later released on bail.
None of the centre's animals were harmed in the incident.