Success in finding information in a website depends not only on the complexity of the information retrieval task per se but also on the way information is made accessible. We explored the role of navigation menus when performing information retrieval tasks. We compared expandable menus with sequential menus. Expandable menus preserve the full context of choice while the user is browsing. Sequential menus provide only partial context. Task complexity was manipulated along two dimensions: path length and path relevance. Path length leading to the target information was varied using different levels of depth. Path relevance - based on semantic similarity - is the relevance of the optimal navigation path to the search task. In general, results show benefits of presenting expandable menus giving fully contextual information when retrieval tasks are highly complex. More specifically, with expandable menus, highly complex retrieval tasks with high path length and low path relevance are more efficiently performed than with sequential menus. Furthermore, users are also less disoriented with expandable menus. A practical implication is that for complex websites path relevance and expandable navigation menus are important usability considerations.