Apex carnivores, including Pumas (Puma concolor), play a key role in ecological communities. Pumas have variable foraging patterns across their extensive range and are known scavengers. A recent review of Puma diet and predation studies documented a total of 48 mammal prey types representing 9 of the 13 orders found in North America, but excluding marine mammals (Orders Cetacea and Sirenia, and Clade Pinnipedimorpha) or tapirs (Order Perissodactyla). This report documents what is, to the best of our knowledge, the 1st observation of a Puma feeding on a marine mammal, a Harbor Seal (Phoca vitulina). Pinnipeds, as hunted or scavenged prey, could be a significant resource for Pumas in coastal areas and should be a focus of future studies. Novel observations of prey items, such as this, are important to document as they expand our understanding of apex carnivores and the effects they have on ecological communities.