First the ditcam question - you can get pretty good results with a Canon A75 (3mp) or A85 (4mp) using Canon's own WP-DC30 housing. I bought my wife an A85 outfit recently for a total of $376
Second, the manatees - The only place you may "legally" approach, swim with and or touch a manatee is in Citrus County. There are daily tours on both Kings Bay and the Homosassa River. You may also strike out on your own in your own boat or on a rental boat.
The tours are all done on snorkel gear since only surface interaction is allowed. You may not dive down a manatee or touch it with more than one hand under the federal guidelines.
The best Manatee encounters take place on the coldest mornings.
I generally suggest you go on a guided tour for your first encounter. This allows you to see the proper way tointeract and see where the encounter areas are (not to mention a fully enclosed pontoon boat with hot cocoa and doughnuts is far better than an open jon boat on a cold morning).
There are numerous tour operators in the area, some good and some not-so-good. The two guided tours I suggest are:
Birds Underwater (
http://www.birdsunderwater.com) and Aquamarine images (
http://www.aquamarineimages.com/)
For a rental boat, the nicest on the bay are from the Port Hotel Dive Shop (800-443-0875)
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