Hi as everyone seems to be recommending, head to Eagle Beach it is stunning, beautiful white sand, turquoise waters, great for swimming or taking a nice long walk and stop in at any number of beach side restaurant/bars for a nibble or a cool drink. If you are into snorkeling and you have access to a car I would head north to Arashi or Malmok beaches where you can park and grab one of the palapas for shade (bring a picnic lunch), shouldn't be that busy at this time of the year. You can enter the water from the beach and you will find a huge coral reef (not very deep) and see the most amazing fish in every color. If you don't have access to a car I would recommend booking a sail on one of the catamarans that will bring you to these locations. My husband and I always book the Dolphin located at Delphi Watersports in front of the Hyatt on Palm Beach. Ask for Jhon. Also Captain Ronald is a great guide and if you are a new snorkeller he will send one of the crew with you underwater. Great sail, they will take you up the north coast and what a great way to see and enjoy this gorgeous island.
Also if you want to see the other side of the island it is well worth it, rent a jeep or take a tour really spectacular.....
Hope this helps, don't hear too many complaints about this island, there really is something for everyone!!!!
arubadreamin