A friend of mine just got back from a Western Caribbean Cruise that ported in Costa Maya, Mexico and told me about a great day trip. They booked a resort called the Maya Chan for the day. The resort provided transportation from the ship and back as well a day of fantastic beach fun and great service. You can use most all of the resorts facilities, there is a great inexpensive spa (or beach massage) , wonderful authentic Mexican lunch buffet, shaded beach lounge sofas, all drinks and non motorized water sports included.

They (my friends)  are scuba divers and I understand that that too is available at this fun resort. You should contact the Maya Chan well in advance to secure your spot.

The link is  http://www.costamayabeachresort.com/