I can not recall ever seeing this before. My son was fishing today with mono line that was bought and spooled this past April and only used about 3 trips. It became difficult to set the hook due to the line sinking. All line near the boat immediately sank so that on a hook set it just simply pulled on the sunk section of line. Have any of you experienced that before? What might cause such a thing? All that I can think of is the line became waterlogged.