Platypus
When on land, the platypus lives in burrows on the river banks. These holes are between  and  long. It makes these holes in the river bank a little above the water. It likes them hidden under roots. When a female platypus is pregnant, the female makes much larger holes, up to  long. She blocks the tunnel with earth at several places. At the end of the tunnel, she builds a nest out of reeds for her eggs.