How do snails survive in wetlands?

All snails need water to survive. I doubt that they will survive lack of water. First, water snails have to live in water, or else they will dry up (I know this from experience, because once my water snails crawled out too much that they crawled out of the aquarium. I found them underneath the dinner table, dried up like un-cooked pieces of macaroni.). I know garden snails will drown in water, but without water they dry out as well, and will go inside their shells and won't come out. So both types of snails won't be able to survive lack of water, in my opinion.