Boolboonda Tunnel is an abandoned heritage-listed railway tunnel at Tunnel Road, Boolboonda, Bundaberg Region, Queensland, Australia. The tunnel is 192 metres in length making it the longest unsupported man-made tunnel in Queensland. Its construction represented an important engineering feat for rail transport in Queensland. It was built from 1881 to 1884 by O’Rourke & McSharry. It is also known as Boolboonda Railway Tunnel and SEQ-6Q 1. It was added to the Queensland Heritage Register on 24 September 1999
The Boolboonda Railway Tunnel opened 12 November 1883 following a construction period of two years. It was built by Queensland Government Railways as part of the Bundaberg to Mount Perry railway line, constructed to service the Mount Perry copper mines. It took two years to dig and was officially opened on 2 November 1883. The line was deviated in 1960 and tracks removed the following year. The section of the line between Tirroan and Mount Perry closed in 1960 and was removed in 1961.
Copper was discovered in the Mount Perry area in the second half of the nineteenth century. Mining activities led to agitation for a link between the mines of the Mount Perry region and a port. In 1872 proposals of a private railway line were considered, and both Maryborough and Bundaberg vied to secure the line. The Boolboonda Railway Tunnel was driven through the hard granite of the range. This was the first time in the colony where it had not been necessary to line a tunnel, due to the nature of the rock it was driven through. The hard granite rock also meant the tunnel did not require additional support, and it is the longest unsupported (railway) tunnel constructed in Queensland.