In the San Juan's we are pretty much always near shore (it's not that big an area) so should we worry all the time? No! We should pay attention using our heads and our tools.
All the rocks, reefs and shallows are marked on charts, the especially egregious places have buoys, signs, sticks and posts out in the water. Of course with storms, high tides, poor maintenance, things go missing, so we are back to paying attention and using the old noggin.
Once not too long ago we were motoring in flat mirror perfect water at about 7 knots in twenty feet of depth. Up ahead I saw a disturbance (some itty bitty ripples) I glanced at my chart plotter and saw nothing alarming, nevertheless as we neared the ripples I braked and prepared to go full astern.
While watching the depth gauge, suddenly -- there it was -- the depth dropped to six and then four -- and we came to a halt. (no we didn't hit) I stopped, turned and went around the shallow spot.