The sight of a hairy-legged spider scuttling across the bonnet of the car might have been evidence we were in the great outdoors, but something still didn't feel right.
While the spider was wedging itself into one of the door frames, I was checking the map to confirm that we were indeed less than 25km north of the centre of Sydney. But the location of this protected nature reserve is not the only surprise provided by a visit to Ku-ring-gai Chase National Park, one of Sydney's lesser-known natural gems, which happens to be the second-oldest park in Australia, established in 1894.
Named after its traditional owners, the Guringai people, the 15,000ha park has at its heart a flooded river valley, which stretches as far as the coast.
Within the park's boundaries are habitats including open forest, heathland and estuarine riverbanks, making it an ideal sanctuary from the blur of city life.
About 20 mapped walking trails weave across this scenery, including sections of the Great North Walk as it passes through from Sydney to Newcastle.
We were here for one of the guided walks provided by volunteers, who also take turns manning the Kalkari Discovery Centre, near the park's western boundary.
Two of them, Keith Weir and Glenda Clark, were waiting for us when we arrived. Together we headed down the Birrawanna Track, which weaves down to the edge of Cowan Creek, a slow-moving tributary of the Hawkesbury River.
Former Londoner Keith said the park didn't get the recognition it deserved. "Publicity has been a problem," said Keith. "You don't get a lot of national parks like this, especially so close to the city."
We passed thick sandstone boulders, a grove of scribbled gums and pinky-red angophera trees, which have roots that can grow even across rock surfaces.
Between them, Keith and Glenda were able to distinguish the calls of friar birds and grey fantails, and to point out plants used as traditional remedies. Keith said he had tried one such remedy: the blood-red sap of the angophera was meant to numb the gums and help with tooth aches.
"It does feel a bit weird," he said. "But it does work."
After a twist in the trail, Glenda stopped in front of a sprouting grass tree. "This was once like a fridge full of food for an Aboriginal person," she said, explaining how insects would be scraped off leaves and the roots could also be eaten.
Soon we reached the base of the track, a riverside landscape with a carpark, cafes and playgrounds known as Bobbin Head.
We were headed towards a mangrove boardwalk, another of the park's wildlife habitats. The boardwalk is popular with groups from the nearby Gibberagong Environmental Education Centre.
As we reached the bridge, a group of biology students was headed across to record numbers of semaphore crabs - so called because they keep one claw permanently aloft.
I suspected they were signalling that this is a place well worth a visit for its amazing experience of Australian wildlife so close to its biggest city.
Further information: See environment.nsw.gov.au.