Disclosed herein is a waterproof case for protecting electronic devices. The waterproof case includes a flexible waterproof bag attached to a rigid lid that can be opened to allow electronic devices to pass into the bag. When closed, the lid forms a watertight seal that protects the inside of the bag from ingress of water. The lid can include a pass-through jack which allows a user to connect an electronic device, such as an audio device, to an output through the lid. The case may also be incorporated into a flexible attachment system, such as an armband or swimbelt. Methods of connecting an electronic device to an electronic output, such as an audio output, through a waterproof case are also provided.