Ysgramor's sons were caught up in this storm and were separated from the rest of the fleet. The youngest son, Ylgar, and his crew managed to sail through it easily without any casualties. He arrived safely at Hsaarik Head somewhat later than the rest of the crew. 
However, his brother, Yngol and his crew were lost after the storm. Ysgramor was furious and commanded the Sea-Ghosts to surrender his son. As a result another storm rose, Ysgramor ventured back into the Sea of Ghosts. Only after the second storm was over Ysgramor found the wreckage of Harakk, Yngol's longboat. He discovered that Yngol and his crew were killed by the Sea-Ghosts prior to his arrival.
Yngol And The Sea-Ghosts suggests that the Sea-Ghosts were actual creatures and not a simple term for deaths at sea.
- The Elder Scrolls V: Skyrim (Mentioned only)