A new mesh size field is presented that is specifically designed for efficient meshing of highly irregular oceanic domains: archipelagos. The new approach is based on the standard mesh size field that uses the proximity to the nearest coastline. Here, the proximities to the two nearest coastlines are used to calculate the distance between two islands or the width of a strait through an archipelago. The local value of the mesh size field is taken as the width (or distance between two islands) divided by the number of required elements across the strait (or between the islands). This new mesh size fields are illustrated for three examples: (1) the Aegean Sea, (2) the Indonesian Archipelago, and (3) the Canadian Arctic Archipelago.