Hi Wezzie! Never met a jellyfish in all my years there, so probably not to worry. I bow to others who are more into snorkle than I am (we dive), but it wouldn't seem to me the best snorkle haven on earth. Also, NOT to scare you, but do keep in mind, there's quite a current at Hol Chan. Honestly, its harder to dive there than any place I dove anywhere else over the caye. A 50+ gentleman drowned there in February. Keep a guide near you, if it is a rough day. Shark/Ray has always seemed calmer, but that may just be when I went.