Smithsonian Institution
National Museum of Natural History: Ocean Planet
Detailed website that was a companion to a 1995 traveling exhibit of the Smithsonian. Links to lesson plans and other educational materials are at the bottom of the page. Enter the exhibition to explore the world of the ocean.
NOAA
Noaa: Ocean Explorer: Sea Floor
This resource page has numerous links to pictures and videos of the sea floor. Topics include geologic features, habitats, bacteria mats and hydrates.