How does an Unseen Servant move?
1) Does it levitate?
2) Can it move through liquid, such as water? (Related question.)
2b) If so, does it sink? Can it "swim"?
2c) If not, can it move across the water without sinking in?
3) Does it glide across the ground, requiring constant "contact" with the ground?
Best Answer
The game isn't that granular in this case. It moves however it moves, because it is magic. At a given table, the DM can put more definition to it, or players can suggest further detail.
The Unseen Servant isn't a creature. Were it a summoned creature, it would have a stat block with all six stats included. That isn't the case. All we are provided is a Strength of 2, which gives you a limit on what it can or can't carry, or how easy it is to oppose the actions it takes. A human or elf with a strength of 3 would be stronger than an Unseen Servant, for example.
It really isn't necessary to describe it. Insofar as it swimming, the rules are silent, so you can take two points of view on that:
It can swim because nothing in the rules says it can't.
It can't swim, because nothing in the rules says it can.
Pick one. What general philosophy do you prefer?