Portal Diver: The First Break!

Ash only meant to spend the evening fishing.
One minute he is alone on the Columbia River, landing the kind of bass that can make a season. The next, a circle of blue light tears open beside his boat. It looks impossible. It feels impossible. And when curiosity gets the better of caution, Ash is dragged through.
On the other side waits a dark tunnel, strange crystals, and creatures that should belong to nightmares instead of reality. His shotgun can hurt them, but not easily. His old Marine reflexes can keep him alive, but only for so long. The way back is sealed, and the only path forward leads deeper into a dungeon that has no reason to obey the rules of Earth.
Ash does not know it yet, but his portal is only the beginning.
Across the world, more gates are opening near human beings. Each one hides a hostile realm. Each one has a timer. If no one enters, fights through, and defeats what waits inside, the portals will break open and spill their monsters into the world.
Survival will require more than weapons. It will require ordinary people to step into the impossible before the impossible comes for everyone.