since everyone has a gps have many folks learned to pinpoint a submerged top by triangulaion? i still do and find it to be more accurate. Sit on your spot and look off and line up 2 points. The old burned tree might align with the church steeple. now look in another direct and find two other objects aligned. The radio tower lines up with sycamore on the bank. Next time you are looking for the spot motor to where the steeple and burned tree align and stay on that course til you get to where the tower and sycamore line up. There's your spot.