With regards to Tinker's Magic, does water count as unoccupied space?

Is there any official word on whether Tinker's Magic can be used to summon a common item (like a shovel) underwater? Does "unoccupied" actually mean "no solid objects?"

I think if you start counting a space filled with water as "occupied", a huge number of things (including, but also going way, way beyond, Tinker's Magic) will stop working the way anyone expects them to. The impact of that would be so severe that if that were the intent, I think they would have called it out explicitly in the rules on Underwater Combat.

That's my thinking as well. So if an object is summoned in the water, or if a druid wild-shapes from a small creature to a large one in the water, is the water replaced or displaced? I guess it only really matters in a small container; in a sea it wouldn't make much difference either way.

Quote from MongooseGef >>

That's my thinking as well. So if an object is summoned in the water, or if a druid wild-shapes from a small creature to a large one in the water, is the water replaced or displaced? I guess it only really matters in a small container; in a sea it wouldn't make much difference either way.

If you do it out of the water, does the air pressure change?

I don't think there are any game mechanics that would affected, nor do I think adding game mechanics about water displacement would be a good idea, unless everyone at the table wants to deal with that.

Quote from kenclary >>

Quote from MongooseGef >>

That's my thinking as well. So if an object is summoned in the water, or if a druid wild-shapes from a small creature to a large one in the water, is the water replaced or displaced? I guess it only really matters in a small container; in a sea it wouldn't make much difference either way.

If you do it out of the water, does the air pressure change?

I don't think there are any game mechanics that would affected, nor do I think adding game mechanics about water displacement would be a good idea, unless everyone at the table wants to deal with that.

As kenclary pointed out, there aren't any actual rules in the game for this sort of thing, because D&D is (intentionally) not a physics simulator.

But it's worth keeping one very important thing in mind: Tinker's Magic, Wild Shape, and just about anything else that would cause an issue with this are magic. And, by definition, magic does not have to follow the normal laws of physics.