National Geographic: Monterey Bay
Take a dive through a kelp bed in Monterey Bay without getting wet or cold!
The Undersea World of Cocos Island: Island of the Sharks, NOVA Online Adventures
One of the best online adventures on the web; great summary of may different species of sharks, including the Requiem Shark.
The Discovery Channel Onlline: Quest for the Giant Squid
Get the latest on the search for this elusive beast of the sea and learn a lot about squid while you're at it. Great interactive stuff.