Sheppard Software
Sheppard Software: Seals
This site gives an in-depth description of a seal, including its behavior, appearance, reproduction, and classification. The site includes photos and illustrations and an interactive quiz to test your understanding.
Smithsonian Institution
National Museum of Natural History: Arctic Studies Center Mammals Seals
This Smithsonian website has a brief, but thorough, article on the Seal that also includes pictures.