Sharks are not a creature to be feared but instead respected and if you know when they are most prevalent and what draws them close, simply avoiding those times and conditions will make your swimming experience a good one. But, of course, in nature there can always be the rare exception to the rule, so it is also good to swim using the buddy system to maintain a constant vigil of your surroundings.
Here are a few points that will serve you well:
1. Don't swim in late afternoon or dusk or in the early dawning hours of the day. These are prime feeding times for sharks.
2. Don't swim when the water is murky. A day when the water is crystal clear affords good visibility to see what is there with you. Case in point but not about a shark, I was once swimming on a rather murky day when all of a sudden a big splash surprised me and a giant arm came out of the water and then slapped the surface. What was it? It was a large sea turtle slapping his flippers in the water. I was glad it wasn't a shark, but it did teach me a good lesson about swimming when visibility is poor. The big fellow actually just looked at me and then swam back out to sea.
3. Don't swim in the dark for obvious reasons.
4. If you come in contact with a school of fish passing by in your swimming zone, get out of the water until they have passed, then check all around the area before reentering.
5. And it is always a good idea to keep your swimming close to shore. Remember, when you are in the water and you cannot touch the bottom, you become an easy mark for a hungry predator. You're in his territory and can't match his speed.
These pointers are very basic, but it is amazing how many people who are unfamiliar with the Atlantic, usually tourists from inland areas, seem fearless when they go out in the water. These are usually some of the same people who swim when it is too rough and get in trouble with rip currents which can take your feet out from under you and pull you out into the deep. If it happens, relax and the tide will let you go as it heads into deeper water. Then you can swim parallel to the beach until you are clearly out of the pull zone and swim back in to shore safely. The more you fight it, the stronger the pull of the current will be, taking you down with it.
This last comment is one that most of us know, but sometimes someone who has never seen a shark can't tell the difference in the predator and an Atlantic bottle-nosed dolphin. When you see a school of dolphin swimming by, you can usually assume that the sharks are not in the area. While sharks are more dangerous with their teeth, the dolphin is quicker and more agile and will usually win any life or death struggle with the shark by ramming the predator's soft underbelly or inner ear with his battering ram of a head. It's amazing to witness and it resembles a small version of Old Faithful at sea when the strike is made. A day or so later the dead shark usually washes ashore. The final picture gives you a good view of the dolphin, with his almost smiling face and his curved fin, the main giveaway of his identity. Keep in mind that the social-minded dolphin often acts with surfers and swimmers in the water and they even have a reputation for nudging a swimmer in distress to safety at shore.
So, enjoy the beach and ocean but make it a safe visit. If you know what you are doing, tragedy is usually avoided and you'll have great memories to take home. If not, then frankly you have no one to blame but yourself. After all, it's their ocean and has been for thousands of years and they will always act according to their instincts. Now go enjoy the beach.