This is generally the converse situation to the lost guide line, in that the diver loses contact with their buddy or team but remains in contact with the guide line, so is not themself lost. Their first priority is to not get lost or disorientated, and in furtherance of this aim would attach a directional line marker to the guide line indicating the direction to the exit before starting a search. The search line can be tied to the directional maker to prevent it from sliding along the line during the search. The direction for the search would depend on the layout of that part of the cave, and where the missing diver should have been in the group. The search party must consider their own safety first, regarding how much gas they can afford to use in a search, which will depend on the stage of the dive when the diver is noticed to be missing. When searching in darkness, the searches should periodically turn off their lights as this will allow them to see the lost diver's light more easily.
