We just posted a detailed review of a popular waterproof tablet case from DryCASE (in case you've never heard of them, check our DryCASE wiki). It is great for iPad and iPad 2 since You can use all of its functionalities.
The case got a 4.3/5 rating and its available to buy at Tablet2Cases.com for $56.95.
Although you certainly could, this DryCASE bag is not for keeping your food items fresh, but rather to store your tablet so you can use it at the beach, the pool, on a boat, or even while out camping. With flexible plastic and vacuum-sealed technology, this waterproof tablet case will make your device completely water resistant, as well as shielded against dirt, dust, scratches, sand and bird droppings.
For more information see complete DryCASE Universal Waterproof Tablet Case review.