Manatees (or possibly the same manatee) have revisited the Chesapeake several times since then, and one was photographed in the creature, manatees do not swim undulating from side to side.
Manatees (or possibly the same manatee) have revisited the Chesapeake several times since then, and one was photographed in the Patapsco River in 2010. Unlike the reports of a serpentine creature, manatees do not swim undulating from side to side.