The food system of the Caribbean Community (CARICOM) transitioned from plantation-based agriculture to one based on small-scale production and high food imports. Through the ‘25 in 5 Plan’, the CARICOM hopes to reduce its US$ 5 billion annual food import bill by 25% in the next five years, mainly by import substitution. Virtual water analysis has the potential to reveal water consumption and fluxes in food production and trade in the CARICOM to highlight hydro-concerns for the anticipated food import substitution. This study, therefore, analysed the virtual water flows associated with maize production and trade in the Caribbean to explore the implications of import substitution for sustainable water use and food security. Maize production and trade matrix data for the period 2010–2019 were obtained from FAO databases, and virtual water content was obtained from the Water Footprint Network database. Virtual water flow was estimated as the product of the virtual water content of maize and quantity traded between any two trading partners. Net virtual water flows were estimated as the difference between virtual water of imported commodities and that of exported commodities for each Caribbean country and its trading partners. Additionally, the equivalent water demand for full import substitution was estimated. The results showed that maize import to the Caribbean was about twice the regional production and both intra- and extra-Caribbean trade were highly concentrated in few countries. The equivalent volume of water required to support full import substitution, at current yields and consumption, was larger than the total internal renewable water resources for some countries. It is concluded that, while there is room for import substitution and diversification to reduce both cost and risk, water scarcity considerations are necessary and can limit the scale of import substitution for key commodities such as maize. A regional approach that takes advantage of national differences in water endowments and production potential, while enhancing intra-regional trade and diversifying extra-regional sources of supply, should be given urgent attention.