Flooding is natural in wetland ecosystems and urbanization is sprawling into wetlands of Lagos city. Flood prevention and management strategies through structural interventions have not yielded the desired result. The environmental determinist’s argument that nothing is free of the influence of the environment comes to fore. This study focuses on understanding ecosystem peculiarity and man’s influential role at intelligently and adaptively building with nature for eco-social sustainability. The research method employs a mixed method sequential explanatory design. In the first phase, a mailed survey collected the following data (n = 116) in June 2020 from ten residential communities within Kosofe local government area of Lagos state: the attributes of the flooding experienced, causes of flood occurrences, and factors influencing occurrence of floods. In the second phase, equifinality is used to explain the results of analysis of the quantitative data. Findings reveal that ‘flooding’ as an end state may occur from different initial states and in different ways, based on dynamic interaction in the environment. In conclusion, an objective approach to sustainability is one founded on acknowledging the importance of the ideologies of environmental determinism and possibilism. While it is common for the environment to set constraints, man has the choice to intelligently journey with sustainability towards a fulfilling and equitable future.