Day at the beach

So I met with a friend the other day that just happens to be a detector enthusiast and he said that the best place you can go to find all sorts of gold, silver, and coins is a beach. Different things wash up and get buried in the sand. When the tide goes out the beach is left open and if you time it right you can find all sorts of things as can be seen in this video I found. Part two can be seen from the same sight. So the nearest beach is 40 miles away and I know that metal detecting is prohibited but I do have the river down by my mother in laws and my friend says this will work just as well, you just have to be quick.