Chart No. 1 · K 12
Rock awash at chart datum
Dangers
A cross with a dot in each corner is a rock exactly at the level of chart datum — awash at low water.
What it means
A cross (+) with four dots, one in each angle, marks a rock whose top is right at chart datum: it is awash — waves breaking over it — at the lowest tides.
Why it matters
At almost any state of tide this rock is hidden just below the surface. It rarely shows enough to be seen, which is exactly why it gets its own symbol.