This is a very good (and tough!) question which is open to debate. It is not a traditional story in which there are easily identifiable protagonists and antagonists. I think the hole (the earth) can be read as the protagonist, if we read this through the lens of an environmentally conscious reader. The earth is protecting itself or perhaps having its vengeance on those who are destroying it. In this reading, the hole is the protagonist and the people are the antagonists because they are ruining the environment and even their own lives by creating harmful hazardous waste.
I think there could be different ways to read into this story and this question, whether you empathize with the hole or not.