Giant, mysterious hole discovered in the backyard of Riverside home

A Riverside family is dealing with a slight landscaping problem in their backyard: a gigantic hole they just discovered that is 30 to 40 feet deep.

Tasha Jenkins and her boyfriend discovered the hole at their Pennsylvania Avenue house after he began to drain their above ground pool and water began falling down the hole, reports the Press Enterprise.

Riverside Public Utilities told ABC 7 that they believe it is an old cistern, an underground reservoir that collected rainwater. These were common in homes throughout the 19th century and this Jenkins’ house was built in 1905.

So it is either that…or, maybe it is some sort of hatch…amirite ‘Lost’ fans?

Whatever the case, the city also said that the homeowner, and not the city, is responsible for filling the hole.

“At least $1,500 worth of concrete to put to the bottom, so it fills out the bottom, because if we just put fill dirt in there, it won’t solve the problem, it might just make it quicksand,” Alec Damani, who also lives in the home, told ABC 7.