Something similar to this happened to me once. Except instead of riptide or wind or some other condition, it was caused by my own stupidity. I was with a group of people at Virginia beach, when we noticed a herd of dolphins swimming pretty close to the shore. I get it into my head to try and swim out to them. I'm not a strong swimmer, but they didn't look that far out. Long story short, I swam much too far out. I was there with a group of people, they knew what I was doing, but there was nothing they could do to help me. I wore myself out completely swimming back, I crawled onto the shore exhausted. I don't know if there was anything I could have carried to increase my chances.