Enchanted Learning
Enchanted Learning: Earth's Oceans Tides
This site explains what tides are and the difference between Proxigean Spring Tides, spring tides, and neap tides, and how these are formed. Graphic illustrations are provided.
Museum of Science
Museum of Science, Boston: Ebbs and Flows of the Sea
A simple one-page explanation of oceanic tides. Includes instructions for completing a tide-mapping activity.