The Cascade Gardens Boulder Trap, a large concrete-lined pond built in the 1960s, was originally designed to stop logs, boulders, and other debris from traveling downstream during floods.
The boulder trap is the largest body of water along the Hobart Rivulet, and plays a vital role in the daily lives of the urban platypus population. It serves as a year-round foraging location, a meeting place during the breeding season, and a refuge during extreme weather events. Because of this, it’s a popular spot for locals and tourists to see platypus.
A Unique Platypus Viewing Opportunity
In our first meeting with the City of Hobart in November 2020, we highlighted the importance of the Boulder Trap and the need for interpretive signage.
The Cascade Boulder Trap Platypus Viewing opportunity is unique to Hobart, offering people a chance to see platypus in a picturesque garden setting just minutes from the city center. No other city in Australia or the world can provide this.
There is a 75% probability of viewing platypus with minimal disturbance to the animals, and only a minor investment is needed to make it happen:
- Hold the water level in the Boulder Trap at full, overflowing the weir.
- Install interpretive information and risk/regulatory signage in Cascade Gardens and along the Rivulet walking/cycling trail.
Repurposing this existing infrastructure to offer a unique wildlife experience would be a major win for both the city of Hobart and the platypus.
(Hobart Rivulet Platypus Draft Proposal v01.11, 3rd November 2020)
Thanks to a collaborative effort between the City of Hobart, Beaker St Festival, South Hobart Primary School and Hobart Rivulet Platypus, on the 25th September, 2025, platypus signage was installed in Cascade Gardens. The new interpretive signage overlooks the Boulder Trap and includes platypus facts and spotting tips.
Thank you to everyone involved!
Header photo credit: City of Hobart
