I recently saw a really interesting (repeat) episode of History Detectives discussing the Underground Railroad...

This episode did some research on the Charles W. Morgan Whaling ship in Connecticut. Apparently, some escaped slaves used ships that traveled offshore as safe havens. This was particularly useful since it kept the runaway slaves out of the sight of bounty hunters for years at a time.

The researchers found copies of the ships manifest that listed the crew by name and race. One of the manifests of this ship also included the lost brother of Harriet Jacobs, John S. Jacobs.

I, personally, had never considered using ship manifests as a resource in researching runaway slaves ...

Anyway, here is a link to the episode summary!