Seabather's eruption (SBE) is characterized by pruritic erythematous papules on the covered areas of the body that appear within 24 hours after exposure to seawater. SBE is known to be caused by the planula of a thimble jellyfish (Linuche unguiculata) or a sea anemone (Edward siellalineata). We report cases of two adult male triathletes who developed pruritic erythematous papules on the chest and back after a swim training along the coastal waters of Samal island, Davao City. Examination of samples of the seawater revealed multiple planulae or larval forms of cnidarians. The histopathologic examination revealed moderately dense superficial and deep perivascular and periadnexal inflammatory infiltrates consisting predominantly of lymphocytes, few eosinophils and neutrophils. Treatment with a short course of systemic corticosteroids proved beneficial in both patients. A review of published literature regarding this interesting aquatic sports dermatosis was also conducted.