A 43-year-old scallop fisherman from Massachusetts had left arm swelling and blisters. Two days before admission, he had cut his hand while scalloping; then he had cleansed it with the stagnant seawater in which he stored his scalloping knives. The following day, his left arm became edematous, erythematous, and painful, and he was admitted to an outside hospital. Despite treatment with broad-spectrum intravenous antibiotics and topical silver sulfasalazine, the erythema progressed and bullae developed. He was transferred to our hospital, where his physical examination results were remarkable for left-arm edema and erythema from the wrist to the shoulder, associated with multiple large, tense bullae primarily on the forearm (Figure 1). He also had a small superficial laceration at the base of his left thumb (Figure 2). Passive range of motion revealed no pain. Laboratory findings were significant for a white blood cell count of 5800 cells/mm3 without left shift.