Do snails migrate

Most snails can only crawl, even most of those that live in water can't swim.

There are a few however that do swim, and some do it pretty well.

Among opisthobranch snails there are many sea slug groups, the members of which are also capable of free swimming. Often they have developed fin-like structures by means of which the can move like a ray with undulating movements.

As a general rule we could say that a Snail with shell is not able to swim where as a snail without shell might be able to.