Dangers of Snorkelling

So I've been snorkeling a few times and nothing bad's happened. I've seen cool fish and beautiful coral and a few jellyfish that were easy enough to dodge. Yesterday I guess my luck meter was on empty. A few friends and I went to Paradise Cove to snorkel. It has the best snorkeling I've seen on the island. We went out and we're doing fine but there were clouds of baby jellyfish everywhere. It was hard to avoid and I could barely see them anyway so we tons of stings from them. Just little ones so it wasn't the worst thing. We figured it would get better once we hit the deep water but we got there and there was a solid wall of jellyfish in our way and these ones were bigger. (About the size of both my fists together) So we had to turn back. There was also a lot of fragments of fire coral floating on the surface and fire coral stings to so we were getting stung everywhere and there was no avoiding. I was panicking a lot cause I get nervous enough in deep water and now my skin is crawling and I don't know how to avoid it. so all we could do was just swim hard for shore. It was not a good snorkeling day. I put up some pictures of what the fire coral and jellyfish look like here.