The walls and windows of the Esplanade building and the nearby sea wall were tagged with spray paint early yesterday.
Most of the symbols were initials, but pool supervisor Gaye Brooks said some of the graffiti on the front doors was particularly offensive.
The front of a nearby residence was also tagged, but not to the same extent.
In the past couple of weeks, other incidents of damage at the complex included a drinks machine being damaged with an axe and chairs being thrown into the sea.
A seat bolted on to the Esplanade was also unscrewed and thrown over the sea wall recently.
Classic Cafe owner Chris Baker believed the premises were being targeted by young people and said it was time to investigate installing security cameras and lighting.
Mrs Brooks said the most recent damage was by far the worst she had seen at the pool.
"We're used to natural disasters, with large waves coming over the sea wall and closing the pool for four days, but this still takes the cake," she said.
"I'm gutted. I couldn't believe it when I walked down this morning. I think when it happens in a place where people come for so much enjoyment of the scenery - to have it [damaged] like this . . . I would like to know why they did it."
Mrs Brooks estimated it would cost about $1000 of ratepayers' money to clean up the damage. Repairs would begin when the weather improved.
Dunedin police are investigating the incident.
