First, draw the coast.

Then mark the depths.

Pool, holds water at low tide. Rocks, covered at high water. Lighthouse, white flash every 10 s.

Take a fix on the stars.

50°16.8′N 4°59.9′W, 50°18.7′N 4°56.5′W, 50°20.4′N 4°53.0′W, 50°20.8′N 4°48.4′W, 50°25.5′N 4°47.2′W, 50°21.9′N 4°42.6′W.

Keep going past the edge of the chart.

Rule a line from pole to pole.

Unsurveyed, 30°S 150°W. No bottom found, 45°S 135°E.

Then follow it home.

50°03.0′N 4°42.0′W. Traverse closed, error nil.