Every couple of days in early 2024, Leonardo Hummel would free-dive into the shallow waters surrounding Koh Tao, Thailand. Amidst the growing communities of reef fish, Hummel liked to document the progress of the first artificial reefs he'd created and deposited two years earlier while at nearby New Heaven Dive School. The original 9mm rebar had grown multiple times in size, with the accretion of calcium carbonate.Sandra Rubio, one of Leo's colleagues at Black Turtle Dive, remembers the passion with which Leo would speak about his work, and the pride that Hummel took in his creations. "They were like his babies," she says. From an early age, growing up in the Pacific Northwest, Hummel found himself perpetually fascinated by the natural world, origami, and art. These fascinations drove him across the globe - from growing up singing with Seattle's Northwest Boychoir and Vocalpoint! Seattle, to a B.A. in East Asian Studies at Carleton College (and post-college years teaching in Beijing), to a master's degree in Industrial Design at Georgia Tech. Hummel found himself in Koh Tao in pursuit of a dream that managed to fuse all of these passions, crafting beautiful artificial reefs in a project that he dubbed "SeaWeaver." These few handfuls of woven reefs still sitting off the coast of Koh Tao, however, now also serve as a gentle memorial; in March of last year, Leo Hummel, 34, passed away. His parents, professors, and colleagues kindly offered their memories of Leo for this article, in the hopes that it might help keep his work alive.—Hummel detailed his project in a paper, "SeaWeaver: Integrating Cultural Craft and Materials Innovation for Artificial Reef Conservation Strategies," which debuted at the Design Research Conference (DRS) in Boston, in June 2024. Leo's former professor, Georgia State's Lisa Marks, presented the research in his stead."Leo was the kind of person that, if something interested him, he would be in school 24 hours a day, ignoring all his other classes just to do that," Marks says. "I'd come back from Christmas break, and my lab was just covered in these insane laser-cut patterns. And I'd say, what's all this? But that was just his brain."Hummel first met Marks after taking her course on the intersection of industrial design and folk craft. Marks, in her work, combines parametric modeling with endangered traditional handcrafts (a field overwhelmingly derived from women's labor, and largely unconsidered in male-dominated industrial design). Leo soon became Mark's research assistant, and she his thesis advisor. Leo went on to complete his thesis on origami that possesses thickness - such as solar-powered marine lights that could fold and sink beneath the ocean waves, to shelter from coming storms."Because he would obsessively go into these deep dives, he would get burnt out," Marks recalls. "So I'd say: 'Leo. Take three days. Go do some other experiment.' And one of those was this hexagonal structure that theoretically could make kelp farms. And that little pet project got University of Washington interested." In June 2020, the University of Washington and the Nippon Foundation launched the "Ocean Nexus Center," whose stated mission is "to establish social equity at the center of ocean governance;" Leo's mother, who worked at the University, put him in contact with them.Ocean Nexus, as it turned out, suddenly had a travel budget going largely unused due to the COVID-19 pandemic, and could repurpose some of those funds for Leo to develop his work. Amidst a largely academic consortium of anthropologists and economists who study the complexities of human behavior, Hummel's work in fabrication served as a beloved addition.All along the West Coast, forests of kelp - "the sequoia of the sea," both organism and habitat - once grew in underwater canopies so tall and thick that they could be seen from space. But along with another underwater vegetation - eelgrass, a flowering marine plant in more tidal regions - these vast underwater landscapes have seen their once-Olympian numbers decline by as much as ninety percent in just the past few decades. Researchers at University of Washington hoped Hummel's structures of woven hemp could provide a means to anchor the vegetation and allow them a chance to regenerate.Leo's parents, Jeff Hummel and Beatrice Gandara, can't recall exactly how Leo's fascination turned to coral. But in 2021, Leo traveled to Koh Tao to take diving classes with New Heaven Reef Conservation. After countless hours bending rebar in his parents' basement, New Heaven helped him deploy his first full-sized design in 2022. Hummel hoped the reef's shape - a hyberboloid - provided an ideal combination: structural stability, interlacing strands that rendered it a single conductive object, and a woven structure that could be easily modified to accommodate different forms of marine wildlife."Because it was algorithmically driven, he could theoretically change these structures to have the openings be bigger or smaller," Marks explains. By customizing these openings to the local biome, the reef "would attract different types of fish and wildlife that need a certain amount of space, or hiding, or nesting."Although Leo started his deployments at New Heaven, he would later forge a relationship with another local diving organization, Black Turtle, which invited him to weave his reefs and teach classes on their construction in the beginning of 2024. His colleague, Sandra Rubio, described him as an amazing teacher whose passion inspired his students."Whenever we work in coral restoration, one of our main problems is getting the tools we need," Rubio explains. "Sometimes we have to weld, or cut metal, or cast concrete. And we don't really know how to do all these things! So he created this specific design for us to simplify this process, and to be able to create really complex structures without spending a lot of time or having a lot of knowledge about it."Much of Hummel's original design files, in Rhino or Grasshopper, remain on his as-yet-inaccessible computer at his parents' house. But Hummel would also document his creations with posts to his Instagram, @seaweaverreefs, which allowed him to add his own geometric color commentary."It broke my heart to do it but I have mostly switched from 12-symmetry to 10-symmetry weaves," he once explained in a post from January 2024, alongside a photo of a thin metal Star of Goliath nestled inside a decagram. "For a variety of reasons, but mostly because when working at scale, that change ends up saving a lot of material. The structure's stability is still many times overkill so that's unaffected, and only total weirdos who count rotational symmetry will even notice. Good thing I don't know any of those ??."One of the driving forces behind Hummel's dedication to SeaWeaver, meanwhile, was not just to perfect its design, but to ensure its accessibility to the low-resource coastal communities most at risk. Compared to other established artificial reef companies that have patented their designs, Hummel's designs could be woven by anyone, in just a few hours, and with everyday construction material."A lot of motivation for the paper [presented at DRS]," his father says, "was to leave a trail that made it clear that this was his intellectual property, and not something that could be patented in some predatory manner." In the wake of Hummel's passing, his parents maintained his online presence so that future researchers could learn from his work - which they described as "more than a technique: it's a philosophy of ecological intention and social equity." But amongst those who remember Leo, one of the most consistent themes was not his capacity to weave beautiful patterns, but the genuinely decent nature of his character."It's really rare to meet someone as talented and, for lack of a better word, almost obsessive [as Leo]. You meet people that do these deep dives into their work, and they're oftentimes not the best people in terms of how they treat other folks," Marks recalls. "But Leo was just a really, really good person."Last year, while in town for his memorial, Hummel's college a cappella group made sure to visit the Seattle Aquarium. There, unmarked, is one of Hummel's original experiments from three years prior: a nondescript patch of eelgrass, anchored by a weave of hemp. It's the only bundle of eelgrass that has survived, for years, in the entire aquarium."I had the feeling that Leo is like these artists that, when they die, their work gains value," Rubio says. "Sometimes, when someone passes away, they become a legend."Learn more about Leo and Seaweaver at Leohummel.com