Moleskin is sold in Drug Stores and Discount stores, Like Walmart. It is in the foot care supplies area (Dr.Scholls)in the Health and Beauty section. It is a cushion type padding that is soft and has adhesive backing that you peel off and apply to tender areas on the foot. Or put it on the back of your heels or where ever you may be rubbed from your shoes before going out. It must be cut to size (don't forget a little pair of siccors) and then applied to your feet. It is usually waterproof and will not come off unless pulled off. It works great for preventing blisters. I hope this helps.
We are going in July also. Staying at the Caribbean Beach July 7-14.
Another good product is called 2nd Skin. It is especially good if you develop a blister. It is a jelly like substance that allows the skin to breathe. Apply it to the sore spot cover it with a bandage (I recommend a medical tape of some sort). It will save your trip if you develop a blister. Sold almost everywhere.