Chart No. 1 · K 28
Dangerous wreck, depth unknown
Dangers
The hull-and-ribs symbol inside a dotted circle: a sunken wreck considered dangerous to surface vessels.
What it means
A horizontal 'keel' line crossed by three strokes (the middle one longest) is a sunken wreck. Enclosed in a dotted danger circle, its least depth is unknown but it is considered potentially dangerous to surface vessels.
Why it matters
This is the wreck symbol to fear: nobody knows how close it comes to the surface. It is often screened in blue as an extra warning. Never anchor near it either — ground tackle loves old wrecks.