My uncle Bill calls it “getting snarfed” — that unforgettable experience of being swept up by a huge wave, thrashed around like dirty laundry, and then spat onto the beach with a mouth full of saltwater and three pounds of sand in your pants. It’s one way to contemplate the power of the ocean.

Me, I prefer to enjoy the ocean from the shore, where I can gaze out at it, in all of its vastness, and revel in just how little I know about this big, blue, complicated Earth. Given the countless environmental problems wrought by humans on land, I’ve always taken comfort in the ocean’s size and complexity, as though those qualities made it less vulnerable to human meddling.

Sadly, I’ve begun to learn just how vulnerable the ocean really is. In 2003, Nature reported that, due to industrial fishing, only 10 percent of large fish remain in our oceans. Add to that the problems of mercury pollution, dead zones, coral bleaching, and acidification, and the oceans arguably are worse off than their terrestrial counterparts.

Which raises the question, why aren’t we all freaking out about it?

One explanation is that the ocean’s problems are hard to see. The surface isn’t turning weird colors or becoming any less luminous for the devastation that lurks beneath. Nor is it assaulting our other senses, the way toxic dumps and smoggy city skies do.

Beyond even those reasons is the simple fact that humans are a land species. Necessarily, our concept of the ocean is based more on shows on the Discovery Channel than actual experience. And despite any harrowing statistics we might hear, we still picture that underwater wonderland teeming with colorful fish.

But land is deeply embedded in our psyches. It’s land that stars in our historic cultural narratives, like The Grapes of Wrath and Little House on the Prairie. It’s pride in land that fuels the quest for the great American lawn. And it’s America’s national parks — not its marine sanctuaries — that many consider our greatest environmental accomplishment.

Lately, millions of well-intentioned shoppers have begun to connect the food they buy with the land from which it comes. They read the fine print on their vegetables, meat, and dairy to assure themselves that their purchase will benefit the iconic farmer, cow, and beautiful pasture featured on the label. What could feel more wholesome than helping out these friendly, familiar characters, so central to our concept of America?

It’s harder to identify with tuna.

And yet, mysterious though they may be, our oceans sustain us. As renowned marine biologist Sylvia Earle says, “Without the ocean, life on earth would simply not be possible. Should we care about the ocean? Do we care about living?” All told, the health of the oceans affects our livelihood as much as our farms and forests do. The connection just isn’t as apparent.

Which is why the future of our oceans will depend upon the power of our imagination. As was the case when we learned about the hole in the ozone layer, ocean conservation requires us to reach beyond what we know to protect that which we can hardly comprehend.

If we don’t address the crisis of our oceans, all of our other environmental efforts could be for naught. But unlike our efforts to preserve land, if the oceans are to heal, we’ll need to be stewards of more than our immediate surroundings.

The ocean is not anyone’s third-generation farmland, or favorite place to take nature walks, or even a fondly remembered childhood haunt. Yet, how we respond to the crisis of our oceans could determine what comes next in this Choose Your Own Adventure story we call life on Earth.