Mosquitoes are common in almost all tropical countries and they tend to aggregate near still waters. Today, mosquitoes are the cause of Zika and Chikungunya virus epidemics in South and Central America. Dengue is another very common mosquito transmitted infection. To avoid mosquito bites, it is recommended that you wear appropriate garments, and take some Deet along with you. In such locations, there is always a chance you will be bitten by an insect or two but in order to prevent constant itching and pain, take an over-the-counter hydrocortisone cream with you. This steroid works rapidly and can be a life saver.
If you plan to be in the sun, you must wear a sunscreen with a high SPF. Too much sun may give you a great tan, but it can also cause sunburn which can make your holiday miserable. Also consider wearing a wide brimmed hat to prevent the sun hitting your face and upper body. Many people who visit the topics for the first time do not realize how hot and humid the places can be. So drink ample water with you and take a break from the midday sun. Get yourself acclimated to the hot weather by just going out for a few hours each day and this way your body will get used to the temperature.
There really is no need to be vaccinated or to take any antimalarial drugs on a short holiday to most parts of the globe unless there are specific travel directives issued for that particular region. To know if there are any governmental travel warnings, check the CDC site that offers up to date information on areas that are currently going through epidemics.
Finally if you plan to paddle always wear a life vest. Never venture in the water without one. And always tell someone else where you plan to paddle. Sometimes the waves can easily push you out in the middle of the sea. If possible, kayak in pairs and limit your sightseeing to the seashore.