The Portal by Brandon Q. Morris and Tim L. Rey

Tyler Drake has a dream: he wants to find Xibalbá, the legendary underworld of Mayan mythology. In Mexico, he meets diver Adriana Ramírez. They have no idea what a fantastic and dangerous world is hidden behind the portal. If they fails to confront the creatures of this alien planet, the gateway threatens to plunge all of humanity into chaos.

Category: Hard Science Fiction