the basking sharks eat only plankton and other microorganisms. shark attacks are pretty much extremely rare. here in florida ive seen at least half a dozen different kind of sharks (nurse, hammerhead, blacktip, bull, and a few others), none of them particularly aggressive towards humans. the exception would be the bull shark, which has been known to attack humans, and can also survive in salt, brackish, or freshwater. several times ive been fishing and bumped into a nurse shark, which always scares the living shit out of you, but they arent even capable of attacking humans because if the shape of their mouth.
inner-coastal waters average about 3-5 feet deep (or 1 to 1.5 [ish] meters for you metric folk) and you never get used to the sight of a 6-8 foot shark swimming around. its some primal instinct. we dont get anything like the huge basking sharks, or large whales, because our water is too warm. small whales are occasionally seen around the Tampa Bay area, and probably on the Atlantic coast, but i dont get to the east coast much. too many damn tourists.
we also have a lot of porpoises (dolphins) who also swim around with their dorsal fins sticking out of the water, but the fins have a more rounded shape. i think i'd be more scared of a porpoise than a shark anyway, seeing as how porpoises are arguably the 2nd or 3rd most intelligent creatures on the planet, and sharks dont even have a brain (they only have a brain stem) and havent evolved in a few hundred million years. =P