From inter- +‎ insular.

interinsular (not comparable)

1. Between islands.

interinsular m or f (masculine and feminine plural interinsulares)

1. interisland

• “interinsular”, in Diccionario de la lengua española [Dictionary of the Spanish Language] (in Spanish), online version 23.8.1, Royal Spanish Academy [Spanish: Real Academia Española], 15 December 2025