Spray Tunnel is an easy walk just outside Zeehan, following the old route toward the Spray Silver Mine. The tunnel was cut so ore could be moved through the hill, and its odd keyhole shape makes it more memorable than a plain mining cutting.
Bring a torch, but use it gently. Glow worms live inside the tunnel, and once you come out the far side there are old boilers and building remains that pull the walk back into Zeehan's mining story.