I am also going soon and we are trying to decide how much to bring. I am by no means an expert and am trying to get a good feel for this myself. But, based on my first trip and my research for an upcoming trip the break down seems to be: At the resort most things can be charged to cc (diving, rental truck, tshirts, drinks and food). I think most of the larger restaurants and grocery stores also take cc. I guess cash would be more for small restaurants, food trucks, and local vendors. It seems there are some ATMs on island if you need more cash later in the week. You also need some cash for an departure tax from the island ($35 USD per person). It seems to be that the groceries and restaurants are about 150% more expensive than in Denver, CO, maybe some people will disagree with me on that, but I that's my mental impression of general costs. Only you can know how much you want to eat in/out and what types of places you are looking for, but I hope that helps. Definitely interested in hearing the more experienced crowds opinions on this and if there are other cash only things I am forgetting about.