<p>In the Amazon region, inland transportation by small regional vessels is the principal means of transportation. Increases in passengers and cargo weight may affect stability and safety, potentially leading to accidents. This is a concern of the third Sustainable Development Goal (SDG) of the United Nations, which aims the good health and well-being for all. This paper explores the potential effects of the increase in average passenger’s weight on the stability of small regional vessels operating in the Brazilian Amazon. A sample of existing representative vessels operating in Manaus was considered to perform stability analysis for different loading conditions, corresponding to population overweight and obesity scenarios. It was found that even without exceeding the maximum number of passengers of each vessel, these ones may become unstable when average passenger’s weight increases above regulation’s assumptions. A multivariate linear regression analysis between dimensionless ratios of vessels (L/B, B/T, T/D) and passenger density (PAX/L) with the most affected stability criterion (A₂/A₁), suggested potential stability issues. Moreover, the analysis allowed the identification of limits of these ratios that define safe vessel configurations. Charts of limited PAX density and length to beam ratios are proposed to prevent instabilities, using current NORMAM 202/DPC inland stability regulations as reference. This study highlights the need for proactive measures to address safety challenges in developing inland transportation systems.</p>