Earths hadal zone includes marine regions 19,700 to 36,000 feet (6,000 to 11,000 meters) below sea level. The reference to the Greek god of the underworld, Hades, is not coincidentalthese are the deepest regions of our oceans, and one of the least explored areas on Earth. New research sheds light on this dramatic environment and the creatures that call it home despite the extreme conditions. Researchers used a cutting-edge Chinese submersible called Fendouzhe to plunge over 35,700 feet (10,900 m) below sea level and collect hundreds of biological samples from the hadal zone in the Yap Trench, the Philippine Basin, and the Mariana Trenchthe deepest ocean trench on Earth. Of the more than 7,000 microbial species researchers documented in the samples, over 89% were previously unknown. Their study, published March 6 in the journal Cell, highlights surprising diversity in one of our planets most extreme environments. Extraordinarily high novelty, diversity, and heterogeneity were observed in the hadal microbiome, especially among prokaryotes and viruses, which are impacted by both the broader context of extreme environmental conditions as well as the delicate topography in the hadal zone, the researchers wrote in the study. Their work is part of the Mariana Trench Environment and Ecology Research (MEER) project, which they claim provides the first systematic view of the ecosystem in the hadal zone. The hadal zone features extreme pressure, near-freezing temperatures, low nutrient levels, and almost complete darkness. Simply put, extraordinary environmental challenges to life, according to the researchers. Nevertheless, the hadal samples revealed the presence of 7,564 microbial species, of which 89.4% were documented for the first time. The remarkable diversity of the samples was also reflected in the microbes genetics, which revealed a broad range of survival strategies. The paper is one of a trio of MEER studies on hadal zone ecosystems published on the same day. One of the other studies details how amphipods (small shrimp-like creatures) may thrive in the extreme environments of the hadal zone thanks to a symbiotic relationship with bacteria. The other suggests that fish living deeper than 1.8 miles (3 kilometers) below sea level all have a genetic mutation that helps them mitigate the impact of the cold, pressure, and lack of sunlight.This last study also estimates when certain marine creatures first descended to such depths. For example, the researchers propose that eels colonized the deep seas around 100 million years ago, which allowed them to survive the meteorite impact that almost wiped out the dinosaurs and decimated marine creatures inhabiting shallower waters. Altogether, the three studies demonstrate the existence of similar adaptive mechanisms between microorganisms and larger creatures living in the hadal zone. These findings suggest the existence of convergent adaptation strategies to hadal environments that transcend species boundaries and biological domains, the researchers wrote in a commentary on the trio of studies. In other words, the hadal zones extreme environment likely drove unrelated species to develop similar traits.In addition to the microbes, amphipods, and fish, however, the researchers also encountered human litter: plastic bags, soda cans, beer bottles, and even a laundry basket, according to Science. This was deeply shocking to us, Weishu Zhao, an extremophile microbiologist at Shanghai Jiao Tong University and a co-author of the microbial study, told Science. While she and her colleagues noted that deep-sea microbes seem capable of processing some human contaminants, that seems like a small consolation in the face of humanitys footprint reaching the deepest regions of our oceans. Ultimately, the study provides rare insight into the exceptional diversity of a region once believed to be lifelessproving that life really does always find a way.