This is a list of laptop sleeves that are waterproof and compatible with various devices.
11-11.6-12 Inch Water Resistant Laptop Sleeve Bag Protective Case Compatible Acer Chromebook R 11 / Samsung Chromebook 3 / MacBook 12 Inch / HP Stream 11 / ASUS Chromebook 11.6" / 11.6 Inch Notebook Carrying Bag