At 80 years of age, artist Pam Hallandal has become the oldest winner of the the Dobell Prize for drawing.

Hallandal beat 649 other entries and was awarded $25,000 for her work, Tsunami, which was inspired by the 2004 Indian Ocean tragedy.

"It's an attempt to find a way of talking about the power of nature," she said.

This year saw the highest number of artists enter Australia's most prestigious drawing prize, with the 46 finalists on display at the Art Gallery of New South Wales until January.

It is the second Dobell Prize for Hallandal - she won it in 1996 for her piece Self Portrait.

She also judged the prize in 1999.

This year's judge was Melbourne artist, and two-time Dobell winner, Nick Mourtzakis.

"Pam Hallandal's drawing Tsunami engages a subject of monumental destruction and yet in its totality the work achieves a profound equilibrium," he said.

"Infused with a subtle and powerful poetry of form this drawing is a deeply moving work of art."