The largest urban waterfront park project in Puerto Rico’s history, the Parque del Litoral transforms a derelict strip of city land along the Caribbean Sea. The park connects the central business district of Mayagüez to the stadiums and sports venues of the 2010 Central American Games. A primary obstacle to creating a park on the project site was the presence of seven stormsewer outfalls, each beyond repair, exiting through the site directly into the ocean. Damage to the reef from these polluted discharges is so extensive that it is plainly visible on aerial photographs. However, correcting the stormwater problem using traditional civil engineering solutions would have exhausted the entire park budget. Instead, we took a cue from the typical pattern of rivers in undeveloped parts of the island, which flow parallel to the coast before percolating through a variety of wetland and dune habitats to meet the sea. We proposed using the landscape itself to perform the hydrological work of slowing, cooling and cleaning stormwater on site before it is released to the Caribbean Sea. Pollutants are naturally filtered by microbes that live in the roots and soil of wetland habitats. Different habitats remove different pollutants. This project incorporates the full spectrum of plant communities on the island, from fresh, brackish, to salt water and wet ponds, moist meadows to dry forest. These myriad landscape types create visual and experiential variety, sustaining interest throughout the narrow and lengthy linear park. Another substantial challenge in designing this event-focused park at the periphery of the city was imagining the future of the landscape after the Central American Games end. The landscape design needed to be repurposable and relevant to the long-term constituency of the park. To this end, we designed the extensive parking courts with permeable detailing that allows this acreage to participate in the site-wide hydrology strategies, and with a flexible grid of varied surfaces compatible with proposed future uses such as community garden plots, neighborhood sports courts and playgrounds. Further, the park needed to be urbanistically tied to the existing city structure. Careful study of the city on foot, on two wheels and on four wheels informed the decision to construct a large plaza and amphitheater near the Customs House, extending the street pattern and creating a connected urban fabric from the historic city center plaza all the way to the new waterfront plaza.