Kas Oosterhuis (Oosterhuis Associates) and Lars Spuybroek (of the Rotterdam office NOX) have been going on about it for years. The commission to design the Water Pavilion, a building to house an exhibition about water on the former construction island Neeltje Jans, finally provided them with an opportunity to put these ideas into practice in a permanent structure.

It took a good deal of persuasion on their part to convince the clients (the Department of Roads and Waterways and the Ministry of Transport and Public Works) that building and exhibition should be a single volume, an environment dedicated to the experience of water. In the end they got their way. NOX and Oosterhuis Associates were permitted to build a water pavilion in which nothing would be predictable, no section would be the same and no angle would be square.

‘Liquid’ architecture (the description comes from the American pioneer in cyberspace architecture, Markos Novak) for a themed building about water – it was a dream commission. Nowhere in the world had anyone been given such an opportunity. True, some of the few fully computer-generated buildings realized to date are pretty eye-catching, but the floors and walls are still predominantly straight.

Only now that it is open is it possible to appreciate properly what the Water Pavilion really is: a huge and spectacular three-dimensional media artwork where form and content are intimately related. It is about 100 metres long and consists of two interlocking sections. The first section, Lars Spuybroek’s Freshwater Pavilion (ca. 61 m. long) is clad with stainless steel and has a wavy, elongated, flowing form. It is followed by the Kas Oosterhuis’s Saltwater Pavilion, dark grey, tapered and angular (ca. 42 m.). The far end, which also boasts the only (small) window in the entire pavilion, juts out over the Oosterschelde. The contrast between the two halves is great; whereas Spuybroek’s section looks like a luminous, flexible deformation, Oosterhuis’s is a dark, angular and fixed form.

The main entrance is located in NOX’s section and is positively theatrical: the rounded head of the silvery mass opens outwards in two parts. Next, a narrow, murky hall: a light sluice. The space itself puts one in mind of a glacial crevasse. There is no distinction between horizontal and vertical, between floors, walls and ceilings. Building and exhibition have fused: mist blows around your ears, a geyser erupts, water gleams and splatters all around you, projections fall directly onto the building and its visitors, the air is filled with waves of electronic sound. The first associations that spring to mind are a film set, house parties with smoke machines and stroboscopes and the sophisticated media attractions of Disneyland. Yet there are two essential differences. Firstly, this space is not just a far-out mockup. Floors, walls and ceiling really do twist and turn, as can be clearly seen outside; their forms are just as liquid as the water flowing past the pavilion. Secondly, the special effects here are not mere passive entertainment. The Freshwater Pavilion – or more accurately, the electronics incorporated in it – is driven by the visitors.

This activation occurs directly by means of levers and switches that operate projections. Four people, each with their own lever, can transform a virtual blob by pushing and pulling. Switches generate a ripple of waves in the projection of a grid around the hand or foot that touches them. In both instances the affinity with the pavilion’s architecture is obvious: it, too, is unstable, a (computer-generated) deformation. Architecture and media have fused here. But even those who do not operate any switches provide input to the building.
In the Freshwater Pavilion sheer physical presence is enough to activate the software; walking back and forth triggers sensors and projections on one’s body. Spuybroek introduced these possibilities quite deliberately. He detests interactive media that can only be operated by one person at a time, thereby condemning other viewers to passivity; nor did he wish to exclude people with a phobia of switches and levers.
Every action works on various levels: ‘locally’ and immediately in the direct deformation of grid or blob, and further away in disruptions of light and of sound. Every act has far-reaching consequences: the more people, the more activity and the faster the light pulsates through the building.

Biorhythm
Oosterhuis’s Saltwater Pavilion is less extreme in form. The space is sculptural but more traditional; a variation on the building as container. There are projections on and behind the semi- transparent walls but the space itself does not ‘flow’ everywhere; access to the lower floor, one-and-a- half metres below sea level, is via an ordinary flight of stairs. The ‘hydra’, a form that winds itself, creeper-like through floors and ceilings, remains a discrete object in the building despite the fact that the control buttons for manipulating light and sound are mounted on it. Only when viewed from the furthest point does the Saltwater Pavilion look truly spectacular. From there the floor slopes like the wing of an aeroplane, the walls run together and the space opens up on all sides so that here, too, the architecture seems momentarily unbounded.

What distinguishes Oosterhuis’s pavilion are the different forms of interactivity employed here. Visitors can navigate through a 3D projection he designed (and which, despite deliberately blurred edges, does not really integrate with the architecture, continuing look like a film on the wall). Moreover, external factors play a role in the ‘behaviour’ of this pavilion. A weather station outside registers data on salinity, tide and wind gusts in and near the Oosterschelde. Processors translate these into commands that slow down or speed up the light and sound inside. They also influence the colour of the light. Thus the ‘biorhythm’ of the building develops. As yet, it is still in its early stages. The pavilion exhibits a basal behaviour which must now, according to Oosterhuis, ‘become more intelligent’. His office is still working on other forms of external influence, such as the possibility of global manipulations via the Internet. In the coming years a lot more software will be added to the Saltwater Pavilion.

Dynamic systems
What a reading of the Water Pavilion makes clear is that, despite some affinities, the ideas of Oosterhuis and Spuybroek differ strongly. Both architects want to create a building that is a dynamic system. But whereas Oosterhuis interprets this as a sculptural building that behaves like a living organism, this is precisely what Spuybroek does not want.

In order to effect a continuous interplay between people and building, he wants a chain reaction that is constantly out of balance. In the Freshwater Pavilion, in the absence of clearly definable floors and walls, people lose their balance and fall; this new architecture demands a new kind of behaviour. The Water Pavilion is the first very large and complex, fully interactive, three-dimensional environment ever built. It is more than a quasi-interactive environment where the user can only choose from a limited number of possibilities supplied by the producer. The software built into the Water Pavilion receives so many different sorts of input that even the makers cannot predict the results. Every moment is different and unexpected. Which makes the Water Pavilion not just an experience but also an unparalleled testing ground for the study of interactivity.