All tagged mouth of the river meaning lyrics

What does "Mouth of the River" by Imagine Dragons mean?

I've heard some bad things about Evolve so far. In fact, some of those things came from reviewers before the rest of us even got to hear the album. Two song reviewers that I trust gave it 3 and 2.5 stars out of 5 respectively, but I still fought to disbelieve that Imagine Dragons could turn out anything less than stellar. And I'm still fighting that. I'm just starting my explanation process. In fact, I've only explained the four singles, and I'm explaining "Mouth of the River" because it was one of ARTV's favorite tracks from the album.