Sea elves, merfolk, and members of other oceanic cultures are not a common sight in surface-world bars because alcohol is dehydrating, and so is being out of the water. Seafolk are an especially rare sight at the Halfway Inn, which is far from any saltwater coastline. Ocean merchants can find many other places to trade that are not on the edge of a large, dry desert.
Even so, everyone is welcome at the inn, and all staff are trained on how to make this cocktail just in case the occasion demands. Brackish and savory, the Seafoam is undeniably unique, and it has proved popular not just with those rare few seafolk visiting the interior of Faerûn, but with all sorts of landlubbers with a nostalgic fondness for the sea!