As Kate Rew says in her book Wild Swim, you can't control the sea; rather you learn to be with it. There's little to compare with the thrill of a stormy sea swim, diving and forging through teetering waves before bouncing in the swell behind the break. The scale and reach of a rock arch is spectacular from a swimmer's eye view as you rocket through on a surge of foam. If you prefer a more meditative experience, you find a deep, inner peace floating in aquamarine on a calm day over constellations of star fish twinkling through swaying weeds.
Reading this will help you to understand more about how the water and waves behave, which is essential if you're in search of this sort of wild swimming sea magic. And of course the vision that's conjured when you think of "the sea" depends on where you live and the particular characteristics of the coast in your local area. Beaches, waves, tides, currents and conditions vary widely from place to place, and from hour to hour, so undertaking some research into the local area is a great foundation.
When starting out, it's always safer to swim on lifeguarded beaches, or at least go with people who are knowledgable and experienced in the local conditions. Find out all you can, and gain experience in relative safety so that you understand your own capabilities. The information here is merely a starting point.