Marine new particle formation involves precursors such as methanesulfonic acid (MSA), iodic acid (IA), and dimethylamine (DMA), yet their nucleation mechanism remains incompletely understood. This study employs theoretical calculations to examine the IA–MSA–DMA system. We propose a nucleation mechanism that underscores the importance of synergistic interactions between sulfur-, iodine-, and nitrogen-containing vapors in driving marine new particle formation.