the ultimate laptop bag is an inflatable orange swimming tow float bag: 1. it looks nothing like a laptop bag 2. it will protect your laptop from water, even completely submerged. 3. it will protect your laptop from falling when side pockets are inflated. 4. you can take your laptop to the beach and not worry about it getting stolen. 5. you can use it as a pillow when hiking or at the beach. 6. much cheaper than a laptop bag.

mine's a Decathlon OWS 500, but i guess that it's as good as any.

Plus, you're not any more ostentatious than any other triathlete at the beach.

warning: all tow floats do leak in the storage compartment, especially if you do swim with it (as opposed to sitting on the beach), so if you really intend to put a laptop in, make sure to put it into a proper water tight sleeve/ziplock bag, e.g. an aloksak.