Every day, the present in the bottom right of your screen will have a new ocean display. Eg present floating in sea: 75 would mean the present is in O75 in the coordinate range of 700-799 and 500-599. You can only find them when in the normal island view that you are usually in. Just skim through the ocean until you find the present and click it to see the prize. Also, each present throughout the world is day specific, meaning if the present says 15 but it is only dec 14, you cant open it until tomorrow!