Final answer:
The Mirim Lagoon is the lagoon along the northeast coast of Uruguay and Brazil, known for its ecological significance and shared natural resources, providing opportunities for binational cooperation.
Step-by-step explanation:
The lagoon that is along the northeast coast shared by Uruguay and Brazil is the Mirim Lagoon (Lagoa Mirim in Portuguese, Laguna Merín in Spanish). This body of water is situated between the southernmost state of Rio Grande do Sul in Brazil and eastern Uruguay.
It is a wide and shallow lagoon, forming a significant wetland area that is parallel to the Atlantic Ocean, with the presence of narrow passages connecting it to the sea.
The Mirim Lagoon, known for high salinity and significant tides, is an important ecological region which supports a diverse range of flora and fauna. It also has a strong influence on the local climate and provides numerous services for the surrounding communities, including fishing and other livelihood activities.
As both Uruguay and Brazil share this vital natural resource, it presents opportunities for binational cooperation in terms of environmental conservation and economic activities like tourism.