A protective case for housing a mobile device is provided. The protective case comprises a top shell that seals against a top surface of a device and a bottom shell that cradles the bottom of the device. The top shell provides a downward extension along its perimeter that fits within a trench or pocket formed around at least a portion of the perimeter of the bottom shell. An underside of the top shell includes a permanently chemically bonded compressible and waterproof film layer. The waterproof film layer is configured to seal directly against the top surface of the mobile device.