Studio Puisto designed a floating birdwatching pavilion within Finland’s Vanhankaupunginlahti nature reserve. Called Piilokoju, the small architecture provides a quiet and discreet space while preserving a commitment to ecological sustainability. The designers have in fact worked in collaboration with Helsinki-based environmental experts so that visitors could be assured a close observation of the birds without disturbing them.

The architects wanted the understated structure to prioritize users’ appreciation of the sorrounding nature – the shelter can accommodate up to forty people at once, suitable for school field trips and gatherings – rather than draw attention to itself. Indeed, the building's strategic location among the wetlands is ideal for birdwatching: visitors can easily camouflage themselves among the tall reeds, while the building provides a discreet vantage point from which birdlife can be observed without being disturbed.

Structurally, Piilokoju was designed as a floating platform, an enclosed wooden raft with concrete piers underneath, pre-built off-site and transported intact to its final location to protect the fragile natural environment . Piilokoju’s walls, floors and roof are made of Finnish larch, a local material known for its weather resistance.