A muffler for marine engines comprising a shell or body composed of two half sections integrally joined to produce an outer chamber having an inlet and an outlet port, an inner chamber in the shell having a perforated or foraminous cone at one end of said inner chamber, said cone establishing communication between the chambers, the inner chamber having laterally extending ports at its end remote from the cone, said ports communicating with the outer chamber and with the outlet of said outer cham...