During the dog days of summer, Zoe would dig. I have been given lots of advice as to why she dug in the dirt outside.
One reason was that puppy was hot and wanted to cool off. That would be reasonable if I had the door closed. The door was open for her to wander in as she pleased.
Another explanation was dog was bored. Far from it. I played with her and took her for walks. I even created little games for her and provided a food puzzle. This is a plastic toy that holds food and deposits nibbles when the toy is rotated and batted around.
My theory was Zoe was building a wine cellar. The hole was behind an arborvitae. Each time I filled the hole, puppy redug the trench. Higher and higher the level of soil rose until the evergreen was raised about 4 inches above all its surroundings. She placed the cellar close to the house and behind the bush.
Perhaps Zoe was really a master gardener.