ABCya
Ab Cya: Latitude and Longitude Treasure Hunt
Use the longitude and latitude clues to find the treasures on the map. The more treasures you find the more challenging it will be to find them.
PBS
Pbs Nova Online: Lost at Sea the Search for Longitude
"The quest for a reliable method to find your way at sea was one of the thorniest problems of the 1700s." Find out about the search for longitude at this NOVA site. Includes interactive Shockwave game, learning activities and more.