<p>Modular floating islands are a promising option for ocean space utilization, offering affordability and sustainability. In this study, the motion response and connector load of a modular floating island in waves were numerically investigated based on potential flow theory. Numerical analysis was performed by adopting a Higher-order Boundary Element Method with the wave Green function. First, the motion response and connector loads of floating islands with different number of outer-module layers were studied. It was found that the single-layer island shows a significant advantage in terms of motion response and has a wider peak frequency range of the vertical load compared to the double-layers island. In addition, it was numerically confirmed that substantial horizontal connector loads can be induced by the horizontal motion responses associated with several dominant Eigen-modes of the floating island. Then, the effect of connector stiffness on the connector loads of the floating islands was also investigated. It was confirmed that the horizontal and vertical connector loads within the floating island can be reduced by adjusting the connector stiffness.</p>