Yeti is found within the viewfinder in the Alaska location. You first need to place someone on the viewfinders looking towards the iceberg. Then wait for them to ask for help finding something (crosshair over their head). Once you are in the zoomed view, ignore (and potentially avoid) the customer's object request. Move the viewfinder to the top right of the screen. His outline is visible in the snowy slopes. Hover the view over Yeti and the achievement will unlock. You need to reach 3 star rank to unlock this destination.