Dynamic Presentation of Navigation Instructions

In some implementations, a mobile device can be configured to provide navigation instructions to a user of the mobile device. The navigation instructions can be graphical, textual or audio instructions. The presentation of the navigation instructions can be dynamically adjusted based the importance of individual instructions and/or environmental conditions. For example, each navigation instruction can be associated with an importance value indicating how important the instruction is. The volume of important audio instructions can be adjusted (e.g., increased) to compensate for ambient noise so that a user will be more likely to hear the navigation instruction. The timing and/or repetition of the presentation of important instructions can be adjusted based on weather conditions, traffic conditions, or road conditions and/or road features so that a user will be less likely to miss an important navigation instruction.