The project occupies a prominent marina 'Dorcol' near the inner port of the city of Belgrade. Located on this particular site on the river near the city center, it is influenced by contrasting hard elements of ship building constructions and on the other side the soft transparancy of water. The design object is inspired by marine flora and fauna with the goal of preserving and further research of the marine life, as well as increasing awareness of environmental issues and importance of marine ecosystem. The systems of aquariums and exhibitions are allocated in the object depending on the temperature requirements for the animals and the plants, as well as the movement of hot air, so e.g. Rain Forest exhibition is in the south part of the object above the ground level and the North Pole exhibition area is located in the north part. The organic concept of the west and north facade of the object, as well as the interior of the aquarium is driven by the idea of water, its movement and flow, reflections of light through water and imagining space with 'water walls'. The formal language of the project combines natural element of object's surroundings-transparency and reflections of water surface, with the built element inspired by an old crane on the site-externally visible truss structure of contemporary architecture. The object consists of three parts joined by a partially glazed steel roof structure spanning over the building-the Aquarium, the Museum, and the Hotel. The main entrance of the ground floor of the aquarium is a large atrium of four stories. User's orientation is enabled by open and fluid space with its focal points of gathering on the ground floor level, which is constructed as a curved surface enabling the visitors of the aquarium a unique experience of walking on the landscape resembling the bottom of the ocean. Each floor has passageways constructed as bridges suspended from a truss roof from which it is able to see the flow of the people on this curved surface-open space. The facades are connected to a system of steel space frames, which support the concrete structures specially constructed to hold a large quantity of water for aquariums. The focus of the architectural design and project is on the complexity of the steel construction holding the tanks and the 'glass box' with the Rain Forest exhibition, as well as the containers on the east facade, which serve as laboratories and office space. The 'moving' west and north facade, constructed as free-form geometry with its organic form resembling a sea creature evokes association of a living water organism with the flowing curves and reflective paneled aluminum cladding resembling fish scales. The surfaces are mathematically subdivided and optimized with the help of various 3D programs and calculated in order to reduce difficulties regarding planarity of the panels.