The author of the best original, unpublished research on the history of Rockdale City will be awarded $5000 from the annual Ron Rathbone local history prize.

The late Rockdale Mayor served as an alderman for more than 40 years and was responsible for the heritage listing of hundreds of buildings.

Cr Rathbone, the author of numerous local history books, set up the prize in 2006 from a trust of accumulated councillor fees he declined to accept before he died in January last year.

The competition aims to foster research and expand the library's local history collection of more than 6000 photographs, 2000 books, manuscripts, maps, drawings, plans, audio recordings and film. Entrants may write about buildings, organisations, politicians, sporting personalities, parks, rivers or events.

Entries close August 1. Entry forms and guidelines available at www.rockdale.nsw.gov.au. Call 9562 1821.

Rockdale Library local history librarian Kirsten Broderick said she often received queries about Pemberton's Baths.

Generations of St George residents learned to swim at the popular Ramsgate swimming spot, which opened in 1924.

"There were diving boards, slippery dips, a sun-baking sandpit and even a small zoo with a monkey," Ms Broderick said. "It was advertised as the first land-based baths. Water was pumped in from the bay."

A Coles supermarket now occupies the site of the baths at 277 The Grand Parade.