In the past year there have been two discrete cases, in very different parts of the world, where rivers have been declared to be ‘legal persons’. Much academic and political attention has been given to the case of the Whanganui River in Aotearoa New Zealand, declared by legislation to be a legal person in March 2017. Less-known is the case of the Río Atrato in Colombia, recognised as a legal person by the domestic Constitutional Court in November 2016. In this paper we interrogate the key features of the legal person model adopted in each of the New Zealand and Colombian cases and explore the challenges posed by those features in the local context. We argue that, although there are obvious contextual differences, there are interesting commonalities in the recognition of rivers as legal persons across the New Zealand and Colombian models, which might herald the emergence of a (loose) transnational concept of legal rights for rivers.