It has been shown that people encounter difficulties in using representations and devices designed to assist navigating unfamiliar terrain. Literature review and self-reported visual and textual data from field experiments are presented. This suggests usability may be limited by assumptions about landmarks implicit in designing representations. Firstly, memorable landmarks are emphasized but route following in situ requires recognizable landmarks. Secondly, little emphasis is placed on differences between landmarks contributing to higher-level concepts related to wayfinding and those directly provoking actions in the environment. Studies analyse landmarks in SMS during collaborative wayfinding to an unfamiliar rendezvous and in images to communicate routes in unfamiliar terrain. Findings illustrate usability benefits for navigation aids. This includes helping users to align a landmark's illustration to their individual perspective in the environment. It also includes identifying landmark salience for shared use by people navigating in dispersed groups to dynamically-negotiated rendezvous.