Buoys mark dangerous areas (in particular invisible dangers in deep waters) together with limited channels. Buoys can be floating, fixed, with or with no light.
Following a danger
- The side marks indicate the limits of the channel to follow in order to navigate within the latter
- Special marks indicate restricted areas
- Isolated hazard marks indicate a specific hazard, while cardinal marks position the danger position with respect to a cardinal point
- Healthy water marks materialize safe areas for navigation