Ten years ago, I had my first exhibition here. I had no idea if it would work or was at all possible, but with a few small steps and a very steep learning curve, I made my first sculpture, called "The Lost Correspondent." Teaming up with a marine biologist and a local dive center, I submerged the work off the coast of Grenada, in an area decimated by Hurricane Ivan. And then this incredible thing happened. It transformed. One sculpture became two. Two quickly became 26. And before I knew it, we had the world's first underwater sculpture park. In 2009, I moved to Mexico and started by casting local fisherman. This grew to a small community, to almost an entire movement of people in defense of the sea. And then finally, to an underwater museum, with over 500 living sculptures. Gardening, it seems, is not just for greenhouses. We've since scaled up the designs: "Ocean Atlas," in the Bahamas, rising 16 feet up to the surface and weighing over 40 tons, to now currently in Lanzarote, where I'm making an underwater botanical garden, the first of its kind in the Atlantic Ocean. Each project, we use materials and designs that help encourage life; a long-lasting pH-neutral cement provides a stable and permanent platform. It is textured to allow coral polyps to attach. We position them down current from natural reefs so that after spawning, there's areas for them to settle. The formations are all configured so that they aggregate fish on a really large scale. Even this VW Beetle has an internal living habitat to encourage crustaceans such as lobsters and sea urchins. So why exhibit my work in the ocean? Because honestly, it's really not easy. When you're in the middle of the sea under a hundred-foot crane, trying to lower eight tons down to the sea floor, you start to wonder whether I shouldn't have taken up watercolor painting instead. (Laughter) But in the end, the results always blow my mind. (Music) The ocean is the most incredible exhibition space an artist could ever wish for. You have amazing lighting effects changing by the hour, explosions of sand covering the sculptures in a cloud of mystery, a unique timeless quality and the procession of inquisitive visitors, each lending their own special touch to the site. (Music) But over the years, I've realized that the greatest thing about what we do, the really humbling thing about the work, is that as soon as we submerge the sculptures, they're not ours anymore, because as soon as we sink them, the sculptures, they belong to the sea. As new reefs form, a new world literally starts to evolve, a world that continuously amazes me. It's a bit of a cliché, but nothing man-made can ever match the imagination of nature. Sponges look like veins across the faces. Staghorn coral morphs the form. Fireworms scrawl white lines as they feed. Tunicates explode from the faces. Sea urchins crawl across the bodies feeding at night. Coralline algae applies a kind of purple paint. The deepest red I've ever seen in my life lives underwater. Gorgonian fans oscillate with the waves. Purple sponges breathe water like air. And grey angelfish glide silently overhead. And the amazing response we've had to these works tells me that we've managed to plug into something really primal, because it seems that these images translate across the world, and that's made me focus on my responsibility as an artist and about what I'm trying to achieve. I'm standing here today on this boat in the middle of the ocean, and this couldn't be a better place to talk about the really, really important effect of my work. Because as we all know, our reefs are dying, and our oceans are in trouble. So here's the thing: the most used, searched and shared image of all my work thus far is this. And I think this is for a reason, or at least I hope it is. What I really hope is that people are beginning to understand that when we think of the environment and the destruction of nature, that we need to start thinking about our oceans, too. Since building these sites, we've seen some phenomenal and unexpected results. Besides creating over 800 square meters of new habitats and living reef, visitors to the marine park in Cancun now divide half their time between the museum and the natural reefs, providing significant rest for natural, overstressed areas. Visitors to "Ocean Atlas" in the Bahamas highlighted a leak from a nearby oil refinery. The subsequent international media forced the local government to pledge 10 million dollars in coastal cleanups. The sculpture park in Grenada was instrumental in the government designating a spot -- a marine-protected area. Entrance fees to the park now help fund park rangers to manage tourism and fishing quotas. The site was actually listed as a "Wonder of the World" by National Geographic. So why are we all here today in this room? What do we all have in common? I think we all share a fear that we don't protect our oceans enough. And one way of thinking about this is that we don't regard our oceans as sacred, and we should. When we see incredible places -- like the Himalayas or the La Sagrada Família, or the Mona Lisa, even -- when we see these incredible places and things, we understand their importance. We call them sacred, and we do our best to cherish them, to protect them and to keep them safe. But in order to do that, we are the ones that have to assign that value; otherwise, it will be desecrated by someone who doesn't understand that value. So I want to finish up tonight by talking about sacred things. When we were naming the site in Cancun, we named it a museum for a very important and simple reason: museums are places of preservation, of conservation and of education. They're places where we keep objects of great value to us, where we simply treasure them for them being themselves. If someone was to throw an egg at the Sistine Chapel, we'd all go crazy. If someone wanted to build a seven-star hotel at the bottom of the Grand Canyon, then we would laugh them out of Arizona. Yet every day we dredge, pollute and overfish our oceans. And I think it's easier for us to do that, because when we see the ocean, we don't see the havoc we're wreaking. Because for most people, the ocean is like this. And it's really hard to think of something that's just so plain and so enormous, as fragile. It's simply too massive, too vast, too endless. And what do you see here? I think most people actually look past to the horizon. So I think there's a real danger that we never really see the sea, and if we don't really see it, if it doesn't have its own iconography, if we miss its majesty, then there's a big danger that we take it for granted. Cancun is famous for spring break, tequila and foam parties. And its waters are where frat boys can ride around on Jet Skis and banana boats. But because of our work there, there's now a little corner of Cancun that is simply precious for being itself. And we don't want to stop in Grenada, in Cancun or the Bahamas. Just last month, I installed these Four Horsemen of the Apocalypse in the Thames River, in central London, right in front of the Houses of Parliament, putting a stark message about climate change in front of the people that have the power to help change things. Because for me, this is just the beginning of the mission. We want to team up with other inventors, creators, philanthropists, educators, biologists, to see better futures for our oceans. And we want to see beyond sculpture, beyond art, even. Say you're a 14-year-old kid from the city, and you've never seen the ocean. And instead of getting taken to the natural history museum or an aquarium, you get taken out to the ocean, to an underwater Noah's Ark, which you can access through a dry-glass viewing tunnel, where you can see all the wildlife of the land be colonized by the wildlife of the ocean. Clearly, it would blow your mind. So let's think big and let's think deep. Who knows where our imagination and willpower can lead us? I hope that by bringing our art into the ocean, that not only do we take advantage of amazing creativity and visual impact of the setting, but that we are also giving something back, and by encouraging new environments to thrive, and in some way opening up a new -- or maybe it's a really old way of seeing the seas: as delicate, precious places, worthy of our protection. Our oceans are sacred. Thank you. (Applause)