Vocalist Jenna McDougall explained the meaning of this song during a an interview with New Noise Magazine
"It's about making peace with your dark side and I talk about the underworld as a physical realm, kind of like a spiritual realm but I wanted to make it a physical place you journey to in your mind and you have to cross uncharted territory to look at your dark side.
Underworld is being talked about a place you reject yourself to, all the feelings you don't want to address are shunned to your underworld. It's kind of where your shadow resides. I'm exploring the idea of venturing there as a physical journey and I imagine in the chorus when I say, 'Down in these depths I'm adding up the numbers. Of all I've suffered in past lives, tied down in the darkness,' I kind of imagine as these dark balloons, like bombs in the way chained to the bottom of the ocean. I imagine as all these memories that you don't want to have anymore that are tied to you and you need to go there and address them and forgive people and forgive yourself.
I think the deepest feeling happens in the most painful period in your life. It's kind of finding a way through the darkness in you and your experience."