The Island of Huvahendhoo at the South East end of the Ari-Atoll is about a mile long running east west and is just about 200 yards wide. We went at the end of the year flying with Monarch Airlines where the seats are just too small for anyone who is a bit fat. However, when we got to the Maldives we forgot all about the flight.
If you can afford it, you should stay in one of the 16 water bungalows on the south side as these are just amazing. We couldn't , so we stayed in the standard chalets which are great too, equivalent to a four star hotel in Europe or North America and each with a truly astounding uninterrupted sea view and its own verandah.
There is a gym table tennis, pool and board games to play. The dive centre (padi) is top notch and the diving itself is stunning. The manta rays are around in october and will be the highlight of any dive you make. There is also sailing and windsurfing within the confines of the lagoon. Snorkeling trips are great fun and the night fishing was a highlight for all on board.
There were no mosquitoes at all when we went. Tiny geckos climbed the walls of the chalets, keeping moths and other insects away from the guests. There were plenty of fruit bats in the trees to keep us and the crows amused.
My most important tip would be to bring boots or sandals to wear whilst in the water. There are lots of urchins and stingrays around and it would be rotten to ruin a holiday by standing on one of them.