A 40-year-old commercial fisherman presented with a blistering second degree burn to the right arm after handling a dredged and undetonated World War I-era sulfur mustard artillery shell. He sustained isolated second degree cutaneous injury requiring wound care and skin grafting. Sulfur mustard, or dichlorethylsulphide, is a vesicant chemical warfare agent that causes significant cutaneous chemical burn and is managed with burn wound care. Long-term effects include cosmetic disfigurement and increased risk of developing cancer. Sulfur mustard exposure is a rare but devastating injury when discarded artillery shells are encountered in coastal waters.