Learn how to read water for danger.

[WillCFish]

You can learn to read Worried Water for danger.
Once I was coming across an unfamiliar Canada lake one day I dropped from half throttle to idle speed and none too soon. I had seen what I call worried water and there was a reef about a foot under the surface. I'm sure many a prop and lower unit have been lost on it to unsuspecting fishermen. Wing dams will do the same thing.