Your phobia of sharks is exactly that -- irrational. Not in proportion to the actual risk. Enjoy the ocean. Consider yourself lucky if you ever have the fortune of seeing one in the wild.
It took me 50 dives in the ocean before I ever saw one -- and that was intentional. We did a shark feeding in St Martin (not an official excursion with Disney) and enjoyed it a lot. After watching the sharks, it became apparent that they had no interest in people. I've been told that most animals, including most warm water sharks are not the eating machine that movies portray. Most have a pretty narrow diet, and people aren't on them.
Now if you're on a surfboard daily, with your arms and legs dangling like a wounded creature, you might get nipped -- especially off of the coast of Central Florida (where I grew up). Again, considering the thousands of surfers in that rough, sandy water, shark encounters are more than rare.
As far as seeing sharks, you probably wouldn't see them unless you were in the water. They don't bob up and down like dolphins. They swish back and forth. I have seen some juvenile sharks corner bait fish near the shore in Vero Beach, but we noticed them from the frothing water and diving birds.
We've always followed the rule of just keeping an eye out for diving birds and large schools of baitfish.
