I have gone to Cozumel 5 times over the last few years and never really needed any mosquito repellent except for once when out on an excursion that took us through the jungle in a jeep. A good repellent is tying dryer sheets or pinning the sheets to the inside of their clothes. I have done that here at home and it really does work! Also, there are mosquito bracelets that I used for the kids and placed them around their ankles instead of the wrists. Here is something to also think about. My nieces just came back from Cozumel and the water is VERY cold right now. Be prepared to not enjoy the ocean as much as you thought. The water is usually on the cool side but it is only in the high 70's to mid 80's right now so the water is a bit cooler than if you were really hot. If you haven't gone to Cozumel before, you might want to check out Chakanaab, Xcaret, or Xel-Ha. Take lots of $1 bills for the taxi cabs into town. The best shopping is in the square by the dolphin fountain. Go down the side streets and do some serious bartering!Don't shop along the street it is very expensive. Be careful of what your 5 year old might see - they have a lot of stuff pertaining to sex (male parts shaped into pipes for smoking). Also, if you would like to eat in town a really good safe restaurant is also located next to the dolphin fountain. A great picture of the sun setting is where the boats dock across the street from the square, it is beautiful. A great gift to yourself would be a message on the beach. It is very private and very relaxing! Another little tid-bit, if you drink soft drinks, just pack you a 24 pack in a suit case because they will run you around $2-$3 for a can over there. Something else you could do with the kids is take a boat over to Cancun and in the mall they have an aquarium place you can pay to go into and see dolphin and sharks. It is really cool! I think the boat ride is pretty quick like 30 minutes or so.