know a place/ person/ thing like the back of your hand
znát někoho/ něco jako své boty
You should learn your river and your places like the back of your hand, a senior officer said. I mean I used to. I could have at one stage recited to you every discharge from the estuary upstream for fifty miles on the north bank of the river, in order.
You must know the moor like the back of your hand. I know it pretty well.
Mapping seems to be rather neglected by many people but I reckon that it is vital if you are to get to know a water like the back of your hand. Cameras and notebooks eliminate the need for a Mastermind memory and confer the vital ingredient of confidence which is so necessary for a concerted attempt at big fish.