THE PLT RPRTD THAT DRG FLT OVER THE OCEAN, HE SMELLED AN ODOR OF SOMETHING BURNING. SHORTLY AFTERWARD, THE ENG LOST POWER. THE PLT WAS ABLE TO GLIDE THE ACFT TO ABOUT 1/2 MI FROM SHORE, THEN HE DITCHED IT IN THE OCEAN. LATER, THE ACFT WAS RECOVERED. AN EXAM REVEALED THE LEFT EXHAUST STACK HAD FAILED & THE ESCAPING EXHAUST GASES HAD RESULTED IN AN ENG COMPARTMENT FIRE.