Boca Catalina is located between Arashi Beach and Malmok Beach. It is a small beach at the north-west coast of Aruba where you can do some nice snorkeling.
There is a small white sandy beach where you can get in or you can go at the rocky side. The rocky side is more rough and getting out is a little bit more difficult there, but it will bring you very nice views underwater. And if you do a little diving, you will see the big eyes of pufferfish.