There is no fun in trying to navigate while clinging to a soggy map in a downpour. Right before your eyes, the route home begins to turn into a greenish-brown papier-mâché clump. Your only hope at this point is that your memory of the route doesn't wash out like the map did.

Several other ways to waterproof a map are:

• Covering it with clear contact paper-making the map waterproof but very stiff and there is no way to now write on the map with a pencil. You can, however, use an indelible ink marker to highlight your route or make notes. When done, it is possible to clean up the marks with a gauze pad soaked in rubbing alcohol.
• Paint on a product called "Stormproof" or other map waterproofing treatments by Aquaseal or Nikwax--available at most map and outdoor specialty stores. The clear chemical coating renders the map waterproof, flexible, and able to be written on.
• A coating of "Thompson Water Seal" or other brick and masonry sealant will make a map water-repellent, but not waterproof.