“From birth, man carries the weight of gravity on his shoulders,” said the pioneering undersea explorer, Jacques Cousteau. “He is bolted to earth. But man has only to sink beneath the surface and he is free.”

Source of both much of our food and some of our fears, the sea has forever sustained and threatened humans. Since the dawn of the industrial era, it has also increasingly been a site of exploration. Advances in technology have helped us better understand what lies below, and, in the 1940s, the advent of Cousteau and Émile Gagnan’s Aqua-Lung forever changed our relationship with the sea. Now, free to experience that sense of liberation described by Cousteau, humans feel more at home submerged—we are, after all, more than 50 percent water.

But for underwater photographers, that sense of freedom comes with challenges. They must quickly get comfortable with uncomfortable situations requiring working with little light and limited air. The reward is pictures like those in this gallery, which appear like postcards from another world.

Members of our Your Shot photography community take us on a trip underwater through their camera lenses, not only into the world’s oceans but also to cenotes in Mexico, a river in Switzerland, and an Austrian lake. Along the way, we meet creatures both great and small, from humpback whales to a skeleton shrimp. The photographers let us peek into a different world but, as witnesses to climate change's affects on the oceans, also provide us with a glimpse into an uncertain future.

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Karen Gardiner is a travel and arts writer from Scotland. Find her at her website or follow her on Instagram and Twitter @karendesuyo.