Water runs in our veins, falls from the sky, breaks on shorelines, rises off rivers, slips into hearts, gleams on windows, shifts into ice, steals through jungles, embraces mountains. Water is a source of wonder, fear, beauty, curiosity, challenge, metabolism, life.

Fifty years ago, I was fortunate to be among the first humans to go beneath water’s surface and spend hours in the depths. My lifelong journey has taken me under the Great Lakes, the Atlantic, Pacific and Arctic oceans, and Siberia’s Lake Baikal. Water is 800 times denser than air and offers no oxygen to breathe. I was protected by wetsuits, drysuits, undersea stations and research subs.

I was there as a physician exploring the physical and mental impacts of the depths on the human body. Throughout, I was on teams supported by the American and Canadian governments and organizations such as Ocean Systems Inc., National Geographic and the Russian Academy of Sciences.

I now understand the dark side to that support: conquest and commercialization of a new frontier.

Beneath the waves, I attended to tasks of observation, note-taking, filmmaking and ensuring my team partners were protected from the multiple stressors of cold, darkness, unpredictable currents and pressures that bend steel.

I’ve spent more than 6,000 hours embraced by water. During hundreds of descents, from beneath the ice at the North Pole to hovering over Titanic, I saw a world hidden from humankind since our long trek out of Africa. There were seamounts and escarpments, creatures of luminous beauty and darkness lasting forever. The spirit of the place went into me.

Water is a lethal, limitless, life-giving frontier. Like all frontiers, it inspires new ways of thinking about the cosmos. It amplifies your capacity to know who you are and who you want to be. Its indifference to human presence clarifies morality. Water enhances your ability to imagine possible futures and select among them. Water makes you better than you are.