Water depth

Water depth is usually indicated on a chart in feet or meters, though fathoms are also used. The reference for depth is the chart datum and is found on the title of the chart. Depths are variable with tide and seasonal variations and should be treated as approximate. Depths can be significantly different than surveyed in areas where sediments are dumped (such as river mouths).

Water depth information can be used by kayakers in many ways. If you are paddling over an area with significant changes in depth, you can keep track of your approximate position by observing the depth of water beneath you and keeping track of changes from shallow to deep and back. Water depth also tells you of areas that may be safe for you to paddle that are not safe for large vessels - if you are in a busy traffic area, paddling in shallow water will keep you away from danger.

Observing the slope of the bottom will help you judge the surf conditions you may encounter at a destination. As well, shallow water will have steeper waves than deep water - this can help determine which route is safest to paddle in rougher conditions.