INT 1 · I 10
Sounding (charted depth)
Depths & contoursCore
A plain figure gives the charted depth below chart datum at that position.
What it means
A number in the water area is a sounding. A smaller following digit is the decimal: 3₅ means 3.5 in the chart's stated depth unit.
Why it matters
Check the chart's depth unit and datum. A sounding is not a guaranteed minimum: water level can fall below predicted datum, the seabed can change, and surveys have limits.