Darwin may have been the 1st scientist to test the survival of land snails in sea water. He never published the results of his experiments as a separate paper, but wrote about them in his letters and summarized them briefly in the Origins of species. You may read a synopsis of his experiments in this paper of mine.
Darwin was trying to determine if land snails could disperse between continents and islands by floating in the sea. This was important for him to know, because he had figured that the snail species on islands had either arrived there from somewhere else where they had originally evolved or had been created separately on each island.
Several mechanisms are responsible for the dispersal of land snails across water. Floating freely or while attached to floating wood may be one of them. I don't know if anyone else has tested the survivability of land snails in the sea (water) since Darwin. I am spending my vacation by the Aegean Sea in a town where the snail Eobania vermiculata is extremely abundant. So, earlier this week I decided to follow in Darwin's footsteps and run a few experiments of my own.
Here are Eobania vermiculata floating in sea water.
There were casualties in the name of science. But before accusing me of animal cruelty, remember that this is a species that is killed in boiling water by the thousands in the name of gastronomical satisfaction.
A full report will await further tests and intense contemplation.