Eden's Wake: Book 2, The Rising Tide Series

Ben's best friend is killed in an underwater implosion on a dying world. Living to die again, the two men reunite and battle for an ancient artifact, a relic which will ensure this planet's survival. Ben crosses a threshold. The world he leaves-doomed; the world he enters-reborn. His wife, Eve, and their bumbling charge, Eleazor, follow Ben through the doorway and blindly into the void. This is Book Two in the Rising Tide series