What is the datum for depth soundings?

The datum for depth soundings refers to a standardized reference point from which depths are measured. Mean Lower Low Water (MLLW) is the correct reference for this context. MLLW represents the average of the lower low water levels observed over a specific period, making it a reliable benchmark for determining water depths.

Using MLLW as the datum provides a consistent base level for navigational charts and nautical navigation, which is particularly important for ensuring safety in marine operations. Precision in water depth measurements is critical for activities like shipping, fishing, and recreational boating because it helps prevent grounding and aids in the planning of maritime routes.

While the other options reference water levels (Mean High Water, Mean Low Water, and High Water), they do not serve as the standard datum for depth soundings in the same way that MLLW does. Therefore, MLLW is essential for facilitating accurate and dependable underwater measurements.