An eyewear retainer includes a flexible elongated arm and a flexible leg extending downwardly from the posterior end of the arm. Elastic bands on the arm receive and engage a wide range of temple arms of eyewear. The leg extends behind a wearer's ear when the temple arm of the eyewear is engaged by the elastic bands. The retainer is buoyant and may include a bulbous buoyancy cell containing a buoyant object on the lateral side of the leg. Thermal medium compartments are attached to the medial side of the retainer arm and retainer leg. Each thermal medium compartment removably contains a thermal medium, such as a cooling medium or a heating medium. A pressure sensitive skin-contacting adhesive is provided on the outer skin-contacting side (i.e., the medial side) of the thermal medium compartment located on the retainer leg. The retainer leg and arm may be comprised of a material including a thermochromic additive and/or a hydrochromic additive configured to change color when the retainer is submerged in water.