Going into the water is no different than taking a hike. Do people know your body surfing? Are there people on the beach, a lifeguard? I am not a strong swimmer. I am, in fact anything but gracile in the water. But I somehow acquired a sense of familiarity with salt water opposite of my deep phobia for clorinated public swimming pools. I learned to RELAX and literally 'go with the flow' much as a judo master uses an opponent's own momentum and mass. Practise the 'Deadman's float' and to conserve energy. Water is no different than a hiking trail. Seek a map; from experienced users, observations of the current conditions etc.