Mary Cairncross Park is a conservation reserve in Maleny on the Blackall Range. The reserve is a 55 hectare area of subtropical rainforest, preserving the remnants of the ecosystem once covering the southern part of the Blackall Range.
The area was heavily timbered from the 1880s, in particular for the prized red cedar trees, and white beech, hoop pine, and bunya pine trees. Logs were taken to a shute to spear the logs down the steep mountainsides of the Blackall Range without too much damage. Nearby McCarthy Shute Road (near McCarth’s Lookout 
) is named after the shute used.
As timber harvesting became less viable and the rainforests heavily cleared, the area became farming land including dairy farming. Mary Cairncross Park was donated by the Tynne sisters and named after their mother Mary Thynne nee Cairncross.
Entering the reserve there is a large parking area next to a large open field. The field has a few sheltered picnic tables along one side, with free BBQs at the top and bottom of the field. The tables appear to be fairly new, possibly updated when the rainforest discovery centre was updated in 2017. On the other side is a playground, and a short walking trail.
There are older picnic tables along the edge of the road along Mary Cairncross Park. The new tables are set in a fair way and have a barrier of trees between it and the parking area. The older tables don’t have shelter or nearby BBQs, but they are across from views of the range over the Glasshouse Mountains. While they are not sheltered, they are set near trees that will offer shade in the afternoon.
The rainforest discovery centre is the main access point into the rainforest and the rainforest walks. The discovery centre was opened in 2017 as a major update to Mary Cairncross Park. The outside of the building has an elevated boardwalk through the mid-level of the rainforest, and access to the viewing deck above the cafe with views over the Glasshouse Mountains.
Enter into the discovery centre with a gold coin donation, with various interactive displays. Open draws filled with samples of crawlies, bird nests, and feathers. Walk around with iPads that pick up features on the walls and provide information about wildlife, and enter the dusk to down room to discover the nighttime sights and sounds of the rainforest.
Through the discovery centre, gain access to the rainforest walks. The walks start with a common section and has a larger outer loop, which is about 3km to walk. A path leads from about halfway around the loop, creating two smaller loops about 1.7km each. The first smaller loop (if going clockwise) is wheelchair accessible.
The walks have various information signs about the different types of trees and sections of the rainforest, such as old vines, towering fig trees, red cedars, and a palm grove habituated with rare Spiny Crayfish. Kids can take a junior ranger eco-hunt challenge booklet to look for answers to questions while walking through the rainforest and discovering facts in the discovery centre.
From the field near the toilets, the Richmond Birdwing Butterfly Walk can be accessed, without needing to go through the discovery centre first. The walk leads behind the playground and to the bottom end of the field. Information panels describe the lifecycle of the Richmond Birdwing Butterfly, a species listed as vulnerable in Queensland, and extinct in two thirds of its former areas.