The Australian sinkhole that's now a secret garden

Penny Walker
Who knew a sinkhole could look so good? - getty

Sinkholes are not generally something that your average person comes across everyday. That is unless you live in Mount Gambier – tucked away in the southeastern corner of South Australia, close to the border with Victoria. 

Renowned for its volcanic landscapes and crater lakes, this small part of the world was formed over 5,000 years ago when volcanoes erupted and lava cooled to form an intricate network of caves. Thus the limestone foundations of Mount Gambier were established and breathtaking lakes took root. 

In the years since the lava caves were formed, their roofs have been slowly collapsing to expose vast areas that have been hidden beneath the surface for millennia. Today, the Mount Gambier and Limestone Coast area is home to an extensive subterranean network of over 50 sinkholes. 

Mount Gambier's Sunken Garden Credit: getty

Among the most impressive of these sites is the Umpherston Sinkhole, also known as The Sunken Garden. While it's unknown exactly when the roof of the cave collapsed to form this massive pockmark in the Earth, there has been a garden here for over 130 years. 

Back in 1886, local farmer James Umpherston took it upon himself to beautify the gaping hole and began to plant vegetation here. Today, you can wander the public park and peer into this hidden Eden from viewing platforms above before strolling down to sit among the greenery and enjoy the fountain (southaustralia.com; free entry). 

The Blue Lake is just one of Mount Gambier's many beautiful lakes Credit: getty

Around the garden you’ll find seating to take it all in, a public barbecue, a sculpture inspired by the fascinating geological processes of the region and at dusk, this peaceful spot comes alive as possums awake and venture into the floodlit grounds to feed. 

But the Sunken Garden isn’t the only sinkhole in the region worth seeing. Here are a few of the best. 

Not a bad spot for a picnic Credit: istock

Cave Garden

One of the most well-visited sinkholes in the Mount Gambier region, the Cave Garden can be found in the city centre in a state heritage area behind the Riddoch Art Gallery. This once served as the original water source for early settlers and today, the pretty waterfall can still be seen tumbling to the floor of the sinkhole – unless you visit during a drought. 

The viewing platforms are suspended over the abyss to give you a sense of how deep the hole is and the surrounding gardens are filled with roses. Every evening there is a sound and light show that tells local Indigenous Dreamtime stories. 

Hell’s Hole

While there’s not much to see from the surface (a small platform sits above it), Hell’s Hole in Lower Glenelg National Park is popular with divers (permit required). This 30-metre-deep sinkhole is filled with fresh, dark blue water. According to local legend, Hell’s Hole was discovered long ago by two travellers making their way through the forest at night. 

Kilsby Sinkhole

Another spot more popular with divers, this 65-metre-deep hole is renowned as one of the world’s finest for its outstanding water quality and exceptional visibility. Located on a local farm, it’s not the easiest spot to find and licence numbers are limited. Site tours are currently under development and should be available soon (kilsbysinkhole.com). If it's good visibility you're after, make sure you also check out Ewens Ponds Conservation Park, which has three spring-fed limestone sinkhole ponds (parks.sa.gov.au).

Ewens Ponds Conservation Park Credit: istock

Caroline Sinkhole

Found in Penambol Conservation Park, Caroline Sinkhole is around 50 metres in diameter and has a walkway built out over the edge so that you can give yourself a dose of height vertigo should the fancy take you. Archaeological digs around the ledges of the hole have unearthed ancient evidence of the local Bunganditj people – an early Indigenous tribe – who probably used it for shelter. During wet periods, water can still be found in the hole.  

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