How to unlock grappling claw? | FAQ - Frequently Asked Questions Far Cry Primal Guide

Climbing places are marked so that you can easily find it.

In order to get to many places you need a special claw that allows climbing in special places and reaching hardly accessible places - for example in upper parts of mountains. You will also need this item in most caves.

Obtaining the claw is very simple. You must complete the "Trapped" mission related to Wogah the Crafter. It is best to do it as soon as possible, right when the mission is unlocked. After doing that you will be able to freely use the claw, it doesn't require any further upgrades.