In 2010, Chile was hit by an 8.8 Richter scale earthquake and tsunami, and we were called to work in the reconstruction of the city of Constitución, in the southern part of the country. We were given 100 days, three months, to design almost everything, from public buildings to public space, street grid, transportation, housing, and mainly how to protect the city against future tsunamis. We started by asking people through participatory design, about 3 possible strategies: forbid installation on ground zero, build heavy infrastructure to resist future tsunamis, or introduce a forest to dissipate the energy of the waves by introducing friction. People raised other issues besides tsunami mitigation: the annual rainfall-related floods, the historical debt of public space and the absence of democratic access to the river. This allowed to identify the right question; there is nothing worse than answering well the wrong question. The forest alternative was massively approved.