What if humans had the ability to breathe underwater?

Just imagine the thrill of breathing underwater! The possibilities are endless. We could wander through coral reefs without ever needing to surface. We could frolic with dolphins and not worry about drowning. We might even unlock the secrets of what Ringo Starr meant in his song "Octopus's Garden." However, as fun as underwater escapades might be, what impact would having gills have on our everyday life?

Not as much as you'd expect. Unfortunately, primates aren’t exactly built for aquatic life. Our limbs are not designed for efficient swimming. We lack the body hair and subcutaneous fat necessary for prolonged water exposure, leading to dehydration and hypothermia. Additionally, most lakes and rivers aren't clear enough for us to fully enjoy underwater exploration. While ocean waters may be more inviting, we would still be limited to exploring only a few hundred meters deep before we enter the bathyal zone—an area where it's dark and the temperature drops to 59°F or colder [source: Britannica].

Living in the shallow waters without pressurized air would be unfeasible. Our eyes and ears are designed for air, making communication underwater a challenge. You could store air in your lungs for a while to talk, but eventually, you'd run out of air to create sound with your vocal cords. And if you've ever dropped your phone in water, you know electronics don’t work well in the depths. Communication would rely on hand signals, but these become hard to use in murky water. Eating underwater would be the hardest part—ever tried having a sandwich at the bottom of a lake?

Despite the challenges, living and breathing underwater would completely alter how we live and build. It would relieve us from the constant fear of drowning. For humans with gills, mining would become much safer with no risk of drowning in flooded tunnels, and underwater construction would be easier and more affordable. No one would drown in floods, and places like Venice, Italy, which is sinking into the Adriatic Sea, could be stabilized.

Perhaps we could even weave water into our infrastructure. If we could breathe underwater, why not convert public transportation into a massive waterslide? Forget buses, trains, and roads—we could have an endless loop of water tubes. You’d dive in at one station, zip through water tubes, and exit miles away. Imagine businesspeople in neoprene suits (to stay warm, of course) hopping in and out of fast-moving tubes between work and home. It would be way more fun than riding the subway, right?

Of course, we’d face some serious engineering challenges. Pumping a giant pressurized water system throughout a city would require enormous energy, but the biggest issue would be the grime. Think about how dirty subways and buses can get. Our water tube system would essentially be like taking a sponge bath on the floor of a subway car, with germs and dirt suspended in the water. Waterborne diseases like cholera and typhus would be a threat, and we'd have to constantly clean, filter, and chlorinate the water.

That doesn’t mean a water-based infrastructure is out of the question. Canal systems could offer significant advantages, especially in coastal cities where they could be naturally cleaned and refreshed by the tides. With everyone wearing stylish neoprene suits and flippers, we could easily zip around the city, escape the summer heat, and reduce our reliance on air conditioning. We would become more conscious of water management and, hopefully, pollute less.

We have the potential to revolutionize agriculture by utilizing ocean water in new ways. If we direct seawater into our canals, we could explore alternative uses for it, such as farming in saline environments—an enormous advantage for humans with gills. At present, saltwater farming is a rare practice, but diverting saltwater inland would create a built-in farming system for growing salt-tolerant crops. Halophytes, like Salicornia bigelovii, thrive in saline soils and absorb freshwater by becoming saltier than the surrounding water. These plants yield 1.7 times more per acre than sunflowers [source: Rozema]. We could also establish small ponds among the crops to support fish and shrimp farming, offering a reliable source of protein.

The most significant advantage of saltwater farming would be the reduced pressure on freshwater resources. Droughts wouldn’t impact our ability to grow saltwater crops. In reality, vast amounts of water are required to irrigate crops for animal feed—1,114 liters per kilogram of wheat [source: Beckett]. However, saline farming would allow us to cultivate fodder for livestock without depleting arable land or groundwater, even in dry regions. Moreover, we could cultivate crops for sustainable but costly biofuels like biodiesel without consuming the water or land used by traditional food crops.

Overall, the ability to breathe underwater would likely have a profoundly positive effect on our lifestyle. We’d spend more time swimming, consume more fish, and become far more conscious about how we manage and use water in our daily routines.