IPA: /ˈʌpˌrɪvər/
KK: /ˈʌpˌrɪvər/
In the direction toward the source of a river, or located closer to where the river begins.
The boat traveled upriver to reach the small village.
In the direction towards the source of a river, opposite to the flow of water.
The boat traveled upriver to reach the fishing spot.
Upriver → It is formed from "up" (meaning in a higher position or direction) and "river" (from Old English "rīfre", meaning a flowing body of water). The word "upriver" means in the direction of the source or higher part of a river.
Think of going 'up' towards the 'source' of a 'river' — that's what 'upriver' means.