I've been chartering in the islands since 1976 and this past trip was the worst for jellyfish and sea lice. I don't complain much, we did a lot of snorkeling in long sleeve shirts, but still got stung pretty badly on the face several times. The comment about marinas and pools is cute, but unless you experienced swimming through the swarms of small jellies, you don't understand. The best I can describe it was like walking through a swarm of gnats that sting. At the dogs, the caves and Maho the water was thick with them. I even saw a local family whose child got stung on the face just minutes after entering the water... about knee deep. They left immediately. It has been worse than I can remember. The beach at Maho was glittering from all the jellies washed up.

http://www.tripadvisor.co.nz/ShowTopic-g...in_Islands.html