Below is information about this spell as it relates to other planes and area of effects (i.e. underwater). Some of the information is pulled official D&D sources (such as books and the twitter feeds of D&D officials), but other information is derived from forums and online discussions. As always, it is up to the DM to decide how they wish to handle spell effects.
None of the acid spells mention water interaction in any way. In addition, the section in the PHB about underwater combat (pg. 198) doesn't mention anything about acid spells behaving differently in water. So officially, there are no rules amplifiying or diminishing the spell effects. In addition, Jeremy Crawford has made a comment regarding a fireball in water that relates to this subject, "Nothing in the rules causes a fireball to vaporize water. Magic ≠ physics. DMs may apply whatever magical/scientific logic they like."
As a DM, I would personally treat acid like fire, "Creatures and objects that are fully immersed in water have resistance to fire damage." (PHB p198)