The sounding numbers show the water level at which tide?

• A. High Water
• B. Low Water
• C. Mid Tide
• D. Slack Tide

Answer: (B)

Soundings are measurements of how deep the water is, i.e., the distance from the water surface to the seabed. To understand how much water you’ll have in a channel, mariners compare those depths to the tide’s extremes. The lowest water in a tidal cycle is called Low Water, and that is the reference point sailors most worry about when checking depths for safe passage. Slack tide refers to the moment when current is minimal, not a water depth level, and High Water is the maximum water level, while Mid Tide isn’t the standard reference used for depths. So the sounding numbers are effectively tied to the water level at Low Water.