Pure copper, tin copper and beryllium copper were exposed to a harsh marine environment, and the effects of fin and beryllium addition on copper corrosion were systematically investigated and compared. The corrosion rate for pure copper was similar with that for tin copper, but significantly higher than that for beryllium copper, indicating an improvement in corrosion resistance due to the addition of beryllium. Pitting corrosion occurred in all investigated materials and the extent of pitting damage was in the order of pure copper > tin copper > beryllium copper. Flaking corrosion was prominent on fin copper plate after long-term exposure and the primary corrosion products in all materials were Cu2O, CuCl and Cu2Cl(OH)(3). The tin content in the inner corrosion layer was higher than in the outer layer for tin copper, whereas beryllium accumulated at the outer layer of beryllium copper, confirmed by auger electron spectroscopy, and related corrosion mechanisms were proposed.