Correction where there is in the code lake_marker_point it should be ‘lake_marker_point2’.
Good news
I just tested the following code on page.php and the custom field shows up. So I know the following custom code does work. But what file do I need to edit for the custom field to show up on the Front-end for all blog posts. single.php appears to not be the correct file.
echo ‘Lake Marker: ‘ .get_field( ‘lake_marker_point_2’ );