If I cast this and the creature moves further than 30ft, is it still active or do they start sinking?

ok why is it that trying to walk on ice is considered difficult terrain, but using this to walk on water considered normal terrain?

and could someone cast water walk then try to walk across a frozen lake or something, and have it not difficult terrain?

My teachers used to ask me questions like that all the time.

The way I read this spell is that it is primarily affecting the creature(s) targeted. It does not affect any effects that would also target them. This means that it would not protect a creature from being swept away by rapids; it would be effectively the same as a creature standing on a fast-moving conveyor belt. They might not become submerged in the water, but it would still carry them away (and potentially smash them upon rocks downriver). Similarly, if a creature with this spell cast on them would become the target of a watery sphere, they would not be able to float away from it the same as if any other creature were trapped in a maximilian's earthen grasp.

Additionally, it says that the creatures gain the ability to walk on water, not that they must use it. A dragon's breath spell, for example, doesn't mandate that the benefiting creature must breathe fire, just that they have the ability to do so. Thus, a creature benefiting from this spell could choose to go swimming.

If you cast Water Walk on the Plane of Water, what happens? There's no "surface" since the water is infinite in all directions, so I'd guess either A) nothing happens or B) you shoot in a random direction at 60ft/per, since the surface is equally close in any direction (i.e. infinitely far away). Alternatively, the inside of a bubble could be considered the nearest "surface" so you'd shoot towards the nearest bubble at alarming rate.

Think of the water as solid ground. Would solid ground that looked like that be difficult terrain to cross? 

Because ice is slippery. 

And no: ice is not a liquid so this spell does not confer any benefits when trying to walk across ice. 

Now hear me out here, could one cast this along with shape water to maybe pseudo surf? Hmmm

Ok I'm going to be the pedant here:

Shouldn't it be "move across any fluid surface" and not "liquid", considering quicksand is not a liquid but instead a non-newtonian fluid and technically a solid (same with lava)? Then again, that might open up the whole gas is also a fluid debate. 

It also might grant you the ability to walk over various oozes though, because I've always maintained those are slime and therefore definitely a non-newtonian fluid. 

Technically ice is "slippery" because the topmost layer in contact with your foot/boot/shoe melts and forms a thin layer of water that you slide across.  Since the spell negates the ability to slip on water, I'd be pretty convinced this could aid in crossing ice or at least negating the part where it's difficult terrain if my players made this argument.

Guys... I messed up. This is reverse gravity and fly if you cast it in the rain. I didn't calculate the minimum speed to have to use it to run in the air, but it has to be faster than 14mph. As for it being reverse gravity, by definition, "submerged" means "below the surface of an area of water" Therefore technically in the rain, you are below the surfaces of sever thousand rain drops... enjoy the pain if you cast this in a storm at sea.

I only had this whole rabbit hole bc I was listening to Critical Role and they cast it in a storm without thinking about the rain they were under. I'm only slightly sad Matt didn't send the Mighty Nien flying lol. 

I love this

Targets must be willing, so, can your horse (or other beast) be a willing target of this spell, since it's too dumb to understand an explanation of what you're doing to it, or would you need something like speak with animalsto make it understand first? This is important for a lot of spells that require a willing creature.

Real thing happening in the campaign we are in at the moment - we are near a whirlpool and someone has figured that what we are after is down below. Its time for a moment of GM - YOU MAKE THE CALL!"  what would you say happens to the party if I cast waterwalk and we try riding down the side of it. 

Quote from Raccoonteur >>

I found this answer while wondering the same thing. "The surface you move across is treated 'as if it were harmless solid ground.' Since solid ground does not flow beneath you (except during precluded non-harmless events such as avalanches, earthquakes, mudslides, and sinkholes), neither is the river treated as flowing beneath you, so you are not carried along."

Another way one might see it is like a rolling treadmill that isn't flat. Solid ground, as you have mentioned, can still slide around, so I believe it is well within reason that the river might act as a fast moving treadmill

does the spell end if the caster either perishes...or end the spell for themselves.....

My thinking ... once cast it last for an hour on the "willing creature" for an hour....irregardless on what happens to the caster

Quick question, lets say, iam a race with a swimming speed, put a kiddie swimming pool on my back and cast water walk on people, can i be like a little carriage while they stand on the water in it? do they still weight something on my back or does the spell cancel it out, i mean they still could grab onto the sides.

im going to cast this on fish

Bout to use this spell to launch a undead megalodon out of underwater so we can fight it easier. 

I can’t wait to get this