If the skyscraper was the highest selfish-manifestation of a culture…, If the skyscraper was the perfect example of how the human race was able to show to it-self, how far it could go in matters of technology and ambition…, If the skyscraper was the emptiness wrapped with the replete, the acme of saturation —during the 20th century—… fostering in a speechless way the statement: “The tallest the better.” Then the skyscraper in the 21st century mustn’t be the rejection of this principles but the culmination of those enriched with the knowledge of how the environmental systems on earth work, and developed with a very clear-mind about the need of preserving the nature that populates the earth. Due to the changes on the ecosystem, because of the voracious lifestyle of the humankind, the closest scenario is one: a notorious increase on the sea tides and the disappearance of many coastlands (according to alarming forecasts, the ocean level should rise from 20 to 90 % during the 21st century with a statu quo of 50cm versus the 10cm of the 20th century; likewise the international scientific scene assets that a temperature elevation of 1°C will lead to a water rising of one meter.) This approach also reveals the undeniable need of a “sustainable” way of living from now on; this means that the resources and the excretions of the civilization must be in a state-of-balance with the surrounding environment to ensure the continuity of the human life as we know it this days; being also ready to survive within the already set-for-the-future conditions (less soil and more ocean). The present proposal understands the need of living in harmony with nature in a sustainable way, this is: To embrace the needs of the present without compromising the ability of future generations to reach their own needs, and due to the emergent global economy, is obvious that this cannot be fulfilled without a co-operative exchange of resources between the different regions of the world. The challenge is to generate a self-sufficient icon of culture able to interact with the environment, exchanging resources & products and working as a balanced living organism: giving and receiving without destroying its own habitat.This project can be unfolded in two different layers, both described above but expressed in design-statements as follows: First, there is a close relation between the entity, its in-side and its surroundings, the living aspects; and the second, the flow around the meaning of the icon by itself, the image of the inverted skyscraper which looking inside-out hides its pride and gets integrated with the horizon, the sea-line.In very practical terms the building can be described as a surface that holds a “sustainable” undersea-scraper. Having the “living space” below the sea level, made-out of independent units that can hold-up a complete dwelling or work station. And the common space with social areas with natural spaces where recreational activities, agriculture processes and farming projects can take place, over and on the sea level. Likewise, all the skin of the building is able to interact with its surroundings getting “tidal power” from its sea-level part —thanks to a double membrane intended to help in flotation matters while transforming the tides into energy,— also “solar” and “wind” power from its upper part, using solar-panels and windmills (this ones can be also spread on the surroundings of the building over the flotation line). The dome-basin shape on the top also works as a rainfall collector, able to wisely manage the water resources. The remarkable property of the project to float or to submerge due to the floating membrane on each one of the units is achieved by a double skin that works as a ballast tank, which controls the weight, by letting air & water going in or out, exactly like a submarine. Recycling, by the way, the organic waste as compost for agricultural matters and using the agricultural waste as feeding resources for the growing animals on the specified areas. The proposal tends to be a renewable answer to various climate conditions likewise getting the best of its environment without destroying it; in short: a very adaptable living-being, towards a new challenge in the way of inhabitting the world.