 Life outside the oceans became impossible as the continents were flooded by rising sea levels and a harsh nuclear winter covered most of the oceans and the shrinking surface landmass of the planet with a layer of radioactive dust, snow and ice many meters thick.A 40-meter thick layer of dead organic matter, the so-called POM layer, covered the oceans.Not a single ray of sunlight penetrated the dense particulate layer that plunged the world into a darkness like none other.