The World’s LARGEST Nature Aquarium: Florestas Submersas

Standing here in front of this nature aquarium, the first thing that strikes you is the size. It is a U-shaped tank with 40 meters length. 145 centimeters high. And it hosts about 160 cubic meters of water. In this video, we take a closer look at how this aquarium is maintained by divers, how it is operated with computer-controlled systems, what kind of technology works behind the scenes and also, how and why this masterpiece was created in the first place. The final and defining work of the father of aquascaping, Takashi Amano. Welcome to the beautiful world of aquascaping on the largest scale. We came to Lisbon to understand not only the technology behind this aquarium, but also what it represents. Because this installation, let me call it that, sits somewhere between aquascaping, ecology and art. The most important thing is what it really communicates about nature. And this, ladies and gentlemen, might be one of the most important projects ever created in this field. And behind an ecosystem of this scale, there's always a team, that makes it work on a daily basis. Leading that team is Tiago, the head of maintenance here. While most of the city is still asleep, their day is already well on the way. They begin work at 6 in the morning, preparing and maintaining this entire system before the first visitors arrive. We have just four hours to work in the aquarium every day, because the Oceanário opens at 10 am. Basically, we do everything the same in the small aquarium at home, but the size is a thing, that changes every way to work. Our job is to divide all the 40-meter aquariums into zones. And we work each zone in different days. We have zone 1, zone 2, zone 3, zone 4 and zone 5. Okay, what is this zone behind us here? So here we have the zone 3. If you think how aquascaping as a hobby was born, well, it started as something very personal. Small glass tanks, usually in someone's home, carefully arranged and maintained. Here, that idea was taken to an entirely different level. This is not a hobby aquarium scaled up. This is a nature aquarium, that had to function as a permanent public exhibition. Open every day, under constant observation and with long-term stability. And that raises a very fundamental question. Can the principles of nature aquarium actually work at this scale, under these conditions? That's really the starting point of this entire project. The idea of creating this aquarium was Oceanário Lisboa. Oceanário went to Japan, to Niigata, and they presented the idea to Takashi Amano. And then, it's like we made a collaborative team. They have the knowledge of the plant growth, the lights, the water changes, the plants needed, the fertilizers. They have all that knowledge. But Oceanário has the knowledge of the water system. The big system... Of course, how it works, because you have been using it before. Exactly! And all that knowledge made us here today, with this beautiful aquarium. We need to work in size. That's the main difference, than the small aquarium at home. We have more than 9,000 hours of diving since 2015. I can see that Maria is already ready. Maria is one of the divers responsible for maintaining this massive system. Because on this scale, you need divers for maintenance. Maria had started to actually trim the Ludwigia glandulosa, so that needs to get in shape and not overtake all the space around it. While she's trimming it, she's collecting it by hand, like all the stems one by one. Every diver has their own tool set. ADA scissors, of course. All kinds of sizes, because here, sometimes we need to reach zones, that are very difficult. There's something special about hearing Tiago say that so naturally, ADA scissors, of course. It showed me how far Mr. Amano's vision has traveled. Not only as an idea, but through the very tools, that still shape these underwater landscapes today. And in a place like this, even a simple pair of scissors becomes part of a much larger story. I'm also using ADA tools in my everyday life. You know how much I love them. This project carries a strong emotional weight, because it was one of the last major projects, that Mr. Amano did in his life. People who worked with him described this as a culmination of his life's work. And they tell me that they actually think that Mr. Amano thought of this the same way. There's a sense that everything he had developed, this Nature Aquarium spirit comes through here. It does not feel like an experiment. It feels complete. This is my first time, that I'm able to actually sit above this aquarium and get this beautiful Nature Aquarium smell. Maria is doing a special trim, okay? Stem by stem. The bottoms of the stems are not very beautiful, so she's covering the cuts. So she's making the cuts, as we go towards the back of the aquarium, she's cutting behind the foreground stems. There's no longer panel in acrylic in the world. It's the longest. You can see probably the seamless connection in between the two acrylic panes. If you're not looking at it, you would probably not even notice it. For the siphoning, you are basically using the same thing. I can see that you are siphoning the water out. I can see that there's a drainage on the other end. I can see that you have like a mesh in this one. This looks like a custom-made mesh, which was actually mounted with cable ties at the bottom. For those of you guys, who are DIY fans, I can tell you that this is the best DIY thing, that I've seen. What do you do after siphoning? Because you know, you're obviously disturbing the soil and it's not gonna be even. Aha, the triangle of your ruler! Yeah! The sand and the rocks are the same, from the beginning too. We didn't add so much sand. They are exactly the same. Is this from the aquarium? Yeah! Are you going to put it back? No! Can I have it? I already stole something! What's really striking here, is that while at home, we can simply take a step back, to see what we're doing during maintenance, here, Maria actually has to climb out of the aquarium and walk down to the visitor's area, to observe the trimming. To see where it needs refinement, where it needs to be shaped further. Are you happy with what's happening here? No, I have to cut a little bit. You do? Yeah, I am. Okay! What do you do with the trimmings, that she has in her hands? We collect them and we put in a quarantine space, just to grow and then we replant. But we'll get back to that later. At first, you might think that this layout was designed on the theme of a river, but it's really not. The layout compositions are changing from an open space, like you see here behind me, to a closed space, like you see in this corner for example. It's almost like this whole layout has a narrative, changing from one thing to another. So the flow, the real natural feeling is accentuated by the way, that these things change from one part to another and nothing is repeating. So this aquascape is not based on a specific real-world location. Instead, this is more like a synthesis of Mr. Amano's entire lifetime of observing nature. It's designed almost like a narrative. Something that unfolds as you move along it. It tells you a story, as it gradually changes character, creating a sense of progression. There's a famous image, it's Mr. Amano laying down in that part. It's exactly here. If you come here in the past month, these are just... On the top. On the top and doing that curve here. What happens is, you let it grow and then you take it out completely? We take it out completely. One year and three months each. And replant with a gardening Japanese technique, with a Wabi-Kuza. Each plant has its own drowning with the shape of the Wabi-Kuzas. We need to put the Wabi-Kuzas right in the right spot. Starting with the right shape. It's not just the trimmings. The main problem is the soil. The soil is very poor at this time. So... It's depleted. Do you use any rootstabs to actually boost it, or do you not need it? We just use the Bottom Plus from ADA. Just a reminder, all this big ball is 110 Wabi-Kuzas. Okay! Okay? The numbers are just astonishing. Just to have an idea. When we plant this one, we plant with 30 centimeters, 40 centimeters, 50 centimeters, 60, 70. Also like physically, this is a very challenging job to do. Because they're in there in twisted yoga positions, as they told me. And they need to actually fit into small places. Look at the Shigonostigma getting in the way. I love this! Trimming this one part for a diver, it's at least one and a half, two hours. It's crazy! The scale of the Soil Aquarium is just amazingly stunning. One of the key ideas behind the Nature Aquarium is that it's not only a design, but it's a controlled environment, in which a message is being conveyed. At this scale, the idea becomes even more complex. The system contains around 12 tons of sand, 25 tons of volcanic rock and 78 tree trunks. Those form a layout with a structure, but it hosts 10,000 tropical fish. With around 40 species in 46 different aquatic plants. And Mr. Mano's idea was that true beauty in nature comes from balance and health, not from control alone. And that philosophy is clearly present here. What Tiago is doing right now, is he's distancing the sand from the front glass, so he can clean at the bottom normally. Because if you push down the sponge, then it will take up small granules of sand and it will scratch the acrylic. He can feel it with his hands, when he's touching it, he can feel that it's slimy, which means that it really has some organic residue with it. It's really great, that is one of the first times, that I don't have to do any maintenance on screen. These are the last moments before the official opening today. The first four hours are really, really hard work for many, many people. So the effort that this team is putting into maintaining this place is heads off. These are the only 30 seconds, that I can be alone and you guys can be alone in this beautiful aquarium. Let's enjoy it, the day starts! It is genuinely heartwarming to see that what Mr. Amano dedicated his life to, bringing nature and the Nature Aquarium closer to people, is truly realized here in Lisbon. Since Floresta Submersas opened, it has welcomed around 10 million visitors, many of them children, who were born after Mr. Amano's passing. It's almost impossible to grasp how a love for nature can build bridges across generations like this. At the same time, this is not only an emotional legacy, but also an extraordinary artistic challenge. To create something, that continues to inspire, evolve and connect with people long after it was first completed. And in many ways, this is exactly the path ADA has continued to follow as a company. From the beginning, its philosophy has remained rooted in a simple, but powerful idea. To help people connect with the beauty, balance and quiet strength of nature. With the Nature Aquarium concept, ADA has not only created products, but a whole culture around observing nature, learning from it and expressing it in a personal way. Their carefully developed top-shelf tools, aquariums, lighting systems, soils and accessories provide aquascapers with precision and freedom to bring their own vision to life. They allow each creator to express something deeply individual, while staying connected to the nature principles, that inspired Mr. Amano's work. Of course, creating something like this is not only an artistic challenge, but also a technical one. At this depth and scale, plants behave differently. CO2 distribution becomes significantly more complex and even basic maintenance tasks require completely new approaches. So let's go down to the basement, where Maria will show us how they preserve and recover the plants, as Tiago mentioned earlier. You bring all the plants that you actually trimmed from upstairs to here? We can do a trim and then they grow. And then we do the trim and then they grow. And then you get to a point, where you cannot trim anymore. Why not? Because you only have the stems. So that's when we cut everything down. From the bottom? From the bottom. We take all the plants down here. Okay. And then what happens, is that we separate them one by one. Stem by stem? Stem by stem. We cut it by sizes and then we tie them in wabi-kuzas. And then we replant it. When we do the re-wrap, we cannot just take everything out and then leave it like that. Of course. Because people will see just a hole. We try to keep everything the same, as in the beginning. And most of the plants are original. Only need to make another 200 of these. More. Or more. Do you want a big aquarium, guys? My first contribution to the Florestas, Mr. Amano's aquarium, I wrapped this. This will go into the aquarium in a couple of days. Okay, so you have the map here, which was drawn by the maintenance team. And you have the different heights of the different stem plants here. And where they go and what they are. This is just Zone 5. Oh, this is just Zone 5? I thought this is... No, this is just Zone 5. Okay. You have six bottles, huge bottles of CO2. How big are they, like... 40. 40 kilos. Is this powering the whole aquarium right now? This is just for the aquarium upstairs. But it powers the whole aquarium from here? The whole aquarium. And this is backup? This is backup. And how long does this last? Usually 12 to 15 days. Okay. So what's happened... So you guys should be happy to change it every eight months at home. So what's happened is that that's why we have a spare. These guys are as big as me, so this is like huge technology. Another important aspect is that this layout was never intended to remain static. From the beginning, it was designed to evolve over time, as the plants grow and the ecosystem stabilizes. What's particularly interesting, is that the team, who was maintaining this aquarium, realized that many of these changes had already been anticipated by Mr. Amano during the initial design phase. That suggests a level of foresight, that goes far beyond just arranging the layout. It's about understanding how a system will develop over the years. As hard as it is to truly grasp the meaning of this system, its water parameters are something very clear and measurable. Let's take a look at what they are. I want to ask you a couple of questions about water parameters. First, what is the temperature of the aquarium? 23.5°C, always. We have a big chiller. So you mostly need to chill the aquarium, not heat, so you never heat the aquarium. No. Can you tell us the Nitrate levels of the aquarium? Very low. Very low, so almost zero. Phosphate, also zero. Yes. Okay, Potassium? 25. 25-30? If it's under 25, we have a little bit more of Potassium. Can you tell me the TDS of the water? 120, 140. This confirms that we have basically the same water, like you do. We are crazy about the water quality here. The main difference in this aquarium and the other small aquariums, is that something that we manage in the water today, we only can see in the next month. We check pH. So basically, it goes like from 6.50-6.60. Okay. To 70, 15, 20, no more than that. Yes, of course. The CO2 gets on about 8.30 in the morning. 8.30 in the night gets off. Okay, and when do the lights come on? At the same time. So you switch on the CO2 together with the lights, not two hours before the lights, as we do in small aquariums. No, there's no need, because our lights, it's not like all the lights. Oh, they come on gradually. Yes. Each projector is 1000 Watts. Oh, this is the old metal halide projector still. Yeah. Let's talk about the filtration and about the way that you change water in this aquarium. Twice a week, we do a big water change. 10 cubic meters. Yes. Twice a week. That is just the water change as a whole. But then we take more water when we are diving. For a week, between 30 to 35 cubic meters of water. For the treating of this water with a sand filter. I'm sorry. No problem, dude. Behind the scenes, Consalo is in charge of the life support system. Making sure everything runs smoothly and stays stable at all times. Now he's stopping something, I can tell. Oh no, he's starting something. Yeah, here all 24 hours, something happening. I feel like I'm in an atomic reactor control station right now. And Consalo is here with us. He's doing basically his opening and closing taps all day long. But it looks really high-tech. We basically control everything from the pumps, or oxidation and reduction. While this room has the least to do with nature, if you look around, we have at least 15 or more monitors around me. It is at the basis of maintaining this natural habitat for all the nice creatures that we have in this aquarium. So enough of technology, let's get back to the nature. This aquarium has changed how this whole hobby is perceived in the world. Before installations like this, aquascaping was mainly associated with hobbyists and competitions. But here, it enters a completely different context. A public institution, visited by millions of people. It shows that aquascaping can exist not only as a personal or competitive activity, but also as a form of large-scale, publicly accessible art. I have seen when we entered this room, that you have like one big skimmer at the end, starting with Zone 1. And then you have skimmers like this, right here, which is for Zone 2, 3, 4 and 5. So what happens to the water, when it comes to the skimmers? It goes directly to our filtration system downstairs. The bags are taking the leaves and the little rocks and all the organic particles. And then we have the sponge. What do you use the sponge for? For dust, that goes off. So you also capture the dust, that comes from the sand and from the soil? Yes. As we've already seen, this 40-meter system is divided into five separate zones. Not only for maintenance, but also because of how the filtration is designed. There are five independent systems, each with its own sump filter, pump, filter bags, activated Carbon, BioBalls, UV filtration and CO2 injection. As we know from Maria, each sump handles a flow rate of around 30 cubic meters per hour, which brings the total system capacity to about 150 cubic meters per hour, across all five units. That means this filtration system circulates the entire volume of the water in 60 minutes. This aquarium is actually very stable, because it's huge. That's one factor. With time, it gets more stable, more stable, more stable. And then we have a lot of parts of the aquarium, that already work kind of like a biofilter. From the perspective of the Wabi-Sabi philosophy, we know that nothing lasts forever. Everything is temporary. On June 30th, 2026, Floresta submersus will close, which is a significant milestone, considering it was originally planned to be running for just three years. Yet, it has been maintained for more than a decade. For those who can, it's still worth seeing this wonder in person. And for those who can't, we hope this video can preserve a worthy memory of it. Mr. Amano has never entered the aquarium itself, while he was building it. But he personally decided on the location of each hardscape element, one by one, standing from the outside and instructing the team members, who were working inside. This kind of decisiveness, how he built it, is best proved by the memory of the team members, who were here telling me, that they were actually building this in one flow. So they didn't stop, they didn't rearrange. Later on, when they came back and started maintaining this aquarium, they were continuously amazed by the full insight of Mr. Amano, of how he actually oversaw and knew exactly what's going to happen with the plants. And that kind of knowledge can be only achieved by decades long of experience in the Nature Aquarium hobby. Let's go a little bit back to Mr. Amano. How was he? He was the one, that had the vision. So if you want the stone in here and not in here, the stone must be here. You know what I mean? The attention to detail... Yes, perfect! How long did it take for you to build this whole thing? 10-11 days. That's surprisingly a short time for that. Yes! And the first time I dived, it was in Zone 5. And I remember the feeling of walking into a piece of art. Like I'm diving in a piece of art. I already knew it was something special. I think that it's beautiful, because everything from the choice of each plant, each species and where they are. It's not random. People do that corner, they walk, they look and they go... And they don't know nothing about aquascaping. There are no words. You have to see it. There's something more emotional in this aquarium. Because it's still the only one. Even the fishes are chosen by Takashi Amano. 10 million visitors that we have in all of these 11 years. We saw that they can feel emotional when they see this aquarium. So the most important is that this aquarium is still doing its job. Sometimes there's people drowning here. There's people crying. There's people just listening to the music that was made especially for this exhibition. Coral Reef Aquarium doesn't do that. It does the wow effect. Exactly! But not the emotional effect and transports you to the nature part. So I think this is like a beautiful arch of life. He has created something, he had a mission and then we are here to take that mission to the next step, to take his message and to preserve his message to the visitors. After Takashi Amano's passing, the responsibility for maintaining this aquarium was gradually transferred to the Oceanarium team. There is no detailed written manual that defines how it should evolve. Instead, the knowledge and the philosophy were passed on through collaboration and experience. That means what you're seeing today is still connected to the original vision. But it's also the result of continuous interpretation by the people who take care of it every day. So at the end, the question is not only what this is, but also how we should think about it. It's clearly an aquarium, but it's much more than that. It's a living ecosystem that changes day by day. Maybe the most important thing is that it makes people look at nature differently. Not as something distant, but as something that can be understood, recreated and appreciated in a deeper way. And that idea, more than anything else, is probably the strongest part of Mr. Amano's legacy. Returning to Lisbon and to Floresta Submersas after nine years has been a really emotional experience for me. Seeing Mr. Amano's work live again gives me a kind of eternal feeling. I don't know about you guys, but I hope that you have the same feeling about this creation and the Nature Experience spirit has touched you in an equal manner. Let me know what you think about it. We'll see you next time. Bye-bye!