Galahad Clark spends a lot of time thinking about what's on his feet. It's in his blood: For seven generations, his family has owned Clarks, the legacy footwear brand responsible for making loafers, slippers, and slides. He's pushed the envelope of the family business in his own unorthodox ways, experimenting with 3-D printed shoes and designs made from upcycled materials. In 2004, Clark launched Vivobarefoot, a company that rose to cult status for its barely-there shoes made for running and hitting the trails, all with soles so thin, every nerve in your foot can feel the rugged earth beneath you.

Now Clark is trying an innovative new material on for size. The Vivobarefoot Ultra Blooms, set to release in July, will be the world's first shoe made from algae biomass.

New material aside, the soft, super-light running shoes use the same design as Vivobarefoot's regular Ultra line. They're flexible enough to scrunch up into a ball, with a thin white sole that's topped by a perforated upper. They're built for use on dry land and in rivers and oceans, where the Swiss-cheese holes flush water out.

"They're like Crocs," says Clark, "but you can run a marathon in them."

Since the Ultra Blooms are molded entirely out of algae-derived Bloom foam, they only come in one color: algae green.

Vivobarefoot

Sassy Slime

Excess algae in lakes and ponds can choke marine life or threaten the supply of drinkable water. It's not a small problem: Last year, Florida declared a state of emergency over the stuff colonizing its coastline. San Diego company Bloom visits waterways with high algal bloom, scoops up some of the algae, then sucks out the moisture and combines it with polymers to create a foamlike material.

The squishy biofoam performs almost exactly like EVA (ethylene vinyl acetate), the polymer material used to cushion most athletic shoes. It's cheap too, with wholesale prices on par with EVA. On top of those benefits, Clark says the foam in each pair of Ultra Blooms will recycle 57 gallons of filtered water back into natural habitats while saving 40 party balloons worth of carbon dioxide by removing the excess algae from the environment.

"It just ticks every box," Clark says. "It's rare to find such a cool environmental initiative that is both cleaning up carbon but also, both cost-wise and performance-wise, just as good as the virgin petrochemicals used on the market."

Vivobarefoot

The $75 Ultra Blooms aren't the only shoes with a sustainability story. Last year, Adidas introduced a seafoam-colored shoe spun from recycled fishing nets and a biodegradable sneaker made from synthetic spider silk. Companies like Rothy's, New Balance, and Nike have experimented with shoes made from upcycled plastic water bottles; and this year, Reebok created a shoe with soles made from dried corn kernels. While the Ultra Blooms will be the first shoe made entirely from Bloom foam, other shoemakers have already started incorporating the material into their construction, swapping the biomaterial for the EVA they used before.

"Ultimately, billions of pairs of shoes could be made with this material," says Clark. "There's that much algae in the world."

In the future, maybe, we'll all wear biodegradable shoes until their soles wear down, crumble away, and return to the earth from which they came. But for now, it's enough to just get people to rethink what makes a shoe. It's not leather or canvas, wool or silk, algae or corn. It's just the thing you put on your feet so you can get out into the world. If it's made from an earth-saving material, all the better.