A portable cooler has a thermally isolating outer shell defining an internal compartment for holding contents to be kept cool, such as, for example, food, drinks and temperature-sensitive medicine. The portable cooler has a door connected to the outer shell for providing unrestricted access to the internal compartment. The portable cooler may have a shelf for holding a cold gel pack to help keep the contents cool. The cooler may also have a plurality of dividers (that are optionally reconfigurable) for defining variously sized storage spaces for the contents. The cooler may have an aesthetically pleasing curved outer shell and an adjustable shoulder strap so that the cooler can be carried on a person's shoulder. Because the cooler is easy and comfortable to carry and because its large swing-open door provides full and quick access to its contents, this cooler is more ergonomic and aesthetic than traditional designs.