Tunnel Creek National Park, Nature reserve in Kimberley region, Western Australia

Tunnel Creek National Park protects a cave in the Napier Range, a limestone remnant of a Devonian reef formed about 350 million years ago. Tunnel Creek, a tributary of the Lennard River, runs underground for roughly 750 m, dissolving a passage up to 12 m high and 15 m wide. Stalactites and stalagmites line the walls, and a ceiling collapse about halfway lets daylight in.

The limestone system began forming around 250 million years ago when the Devonian reef was first exposed, fundamentally reshaping the landscape. The structures visible today took shape over the last 20 million years through ongoing erosion and water movement.

The cave is known as the hideout of Jandamarra, a Bunuba man who resisted European settlement and hid there for two and a half years. A monument about 100 metres from the west end of the tunnel marks where he was shot by the tracker Micki on 1 April 1897. Aboriginal rock paintings remain on the walls, though they are now hard to make out.

Visitors should bring torches and water-resistant shoes, as some tunnel sections require wading through permanent water pools. Water can reach stomach depth in certain spots, so care is needed when walking through.

Five bat species live inside the tunnel alongside freshwater crocodiles that inhabit the large water pools of the system. This unusual mix of flying mammals and reptiles makes the wildlife here particularly noteworthy for visitors to observe.