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?"

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.

My group decided that the summoned item or additional wild shape volume replaces the medium and does not displace it (thought I did cook up a fun role playing scenario where my artificer runs an experiment to determine which one it is with certainty!) 

The explanation is that every bit of matter in the world has a physical form which mortals perceive, and a "resonant pattern". The resonant pattern exists within the Weave of the universe. Both the physical form and the resonant pattern exist simultaneously. So when magic is used to summon a shovel, the resonant pattern of that space is altered to be a shovel, with the extra matter being borrowed from the Weave itself. When the shovel disappears again, its matter is returned to the Weave.