Numerical simulation of the lagoonal currents and virtual particles advection was conducted in order to estimate the characteristics of the water pollution in the lagoon of Funafuti Atoll, Tuvalu. Comparison of the calculated current velocity and water surface elevation and the observed data showed good agreement. The calculated lagoonal currents showed that surface currents were driven by wind. On the reef-flat, the currents were formed by combined influences with wind and tide. Numerical simulation of virtual particles advection indicated that the particles which were installed in the nearshore of Fongafare Island were transported to the west-side of the atoll through a year. In the non-trade-wind season, the high retention of installed particles was calculated in the lagoon.
