No description is given for the “Sea of Despair”, or why it is named as it is. Its brief appearance is simply water, with no features or wildlife or nearby land formations seen.
In "Have Dragon Will Travel, Part 2" Johann acquired information for Heather on the whereabouts of Dagur the Deranged, so she might exact revenge upon him. His intel and map state that he will be buying new ships in the Sea of Despair.
|“||Dagur is set to purchase a fleet of new ships from a group of salty undesirables in the Sea of Despair.||”|