This app was mentioned in 6 comments, with an average of 1.83 upvotes
Map data is cached on the watch, but there's no way to directly control your offline data like you can on the phone. If you open maps while you have a connection, you can scroll around to cache an area and it will stay on the watch for some time.
I would suggest if you're going someplace you haven't been before, do this trick soon before you go, or maps might decide you don't have a reason to keep the data.
There's also OSM offline maps but I can't vouch for it.
I don't think you can save Google maps offline to the watch, I think that's a phone-only feature. This might work: https://play.google.com/store/apps/details?id=com.wearofflinemap.world&hl=en_GB . In fact when I get my Polar I'm going to have to try that.
Nice thing about Wear is that the openness of the platform means weird nonstandard approaches exist.
other things not covered by /u/mhunterchump 's link, and you're asking about the sw3:
>Is the navigation function useful without the phone?
I'm gonna guess that without a data connection, google nav won't work at all. But there's OSM city maps, and a couple other map options you can side-load to the watch if you want to tinker.
>Do the "leave by" alerts work without the phone and, if so, will it use the location of my wear device or phone to determine the time?
I would think as long as you have location service turned on on the watch, and are on wifi, it would. The watch gps should return your location even if the wifi network you're on isn't in the google database.
Also, I know that for any new wifi network, you must authorize on your phone first. Another important question is how wifi connections are handled on the watch when using a public network that requires accepting TOS every time you connect. Haven't seen that answered.
The smartwatch has a GPS.
However apps need to support the GPS function to use it. The smartwatch cant just add the GPS function if the app doesnt support it
So far no map app has decided to implement GPS support on an offline app.
<strong>this</strong> is the closest thing we have on that department but the dev has decided that GPS is only used when the watch is paired to a phone.
No idea why really.
I will probably drop them a line about how little sense this makes considering its an offline map app soon.
Waiting for google to make maps available offline on wear could take ages
Try OSM