We had a very interesting day today. We ran a successful profiling mission. However, about halfway through the mission, Bart realized that the fiber-optic cable was not moving as smoothly as it should. It slowly became clear that the cable was stuck somewhere because even when the robot was driving towards the melthole, we had to spool out the cable instead of bringing it in. This was a serious issue because the snag could cause the cable to be pulled out of the robot causing loss of communications. We have recovery procedures built-in, but we prefer to have communications with the robot because this is an unexplored lake and we like to be able to control the robot at all times. The robot finally came back to the melthole, but the cable was looped around something. After long discussions, we disconnected the cable from the robot and pulled it in. We were concerned about doing this because we did not want to end up in situation where the end of the cable woul get stuck somewhere and we would not be able to pull it in without breaking the end. We still do not what it was snagged on, but we know the direction and distance from the melthole, so we will mark an elliptical keep-out zone in our maps for future missions. It could have been an ablation stake left back from some previous scientific experiment or something natural.