Getting a waterproof bag for your netbook can be an expensive affair, but if you want to be sure that your netbook is safe from both the big squeeze and that sudden tsunami. Here are some of your options.
Pelican 1090-000-186 HardBack Laptop Computer Case

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A metal case on the outside, and foam on the inside will give the best in protection for both waterproofing and crushing.
HP Mini 2140 10" Netbook CaseCrown Double Memory Foam Netbook Case with Shoulder Strap and TSA Approved Combination Lock

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This one is a more stylish choice then the metal option, so if you want something that you can take places without being embarrassed about then this bag may be a good choice. It comes in a variety of colors, and while it says that is for HP minis it will fit most 10 inch netbooks.