In order to use navigation on the watch (I assume you mean Google maps), you have to either have an LTE watch with mobile data on, or be connected to wifi. The watch will not connect to public wifi, so you need mobile data. You should, however, be able to download and use an offline map to the watch. You have to download the offline map to the phone and it will automatically sync to the watch while charging.
In order to use navigation on the watch (I assume you mean Google maps), you have to either have an LTE watch with mobile data on, or be connected to wifi. The watch will not connect to public wifi, so you need mobile data. You should, however, be able to download and use an offline map to the watch. You have to download the offline map to the phone and it will automatically sync to the watch while charging.
