In Roatan you will likely be going to Carnival's new Mahogany Bay dock.
No need for an excursion there. A fantastic new beach is right there within walking distance and it's free. There is a ski lift type ride that will take you over to the beach ($5 all day pass) but it's an easy walk. Beach chairs are free. There is also a zip line ($40) within easy walking distance.
56 Carnival: Mardi Gras, Ecstasy X2, Fascination X6, Celebration, Elation X5, Glory X5, Fantasy X4, Valor, Holiday X3, Imagination, Liberty, Spirit X2, Freedom, Destiny X2, Splendor X2, Dream X2, Conquest, Legend X3, Victory, Sensation, Paradise, Inspiration, Magic X2, Triumph, Miracle X2, Breeze, Sunshine X3
7 Norwegian: Sky, Jewel, Dawn, Epic, Pearl, Breakaway, Getaway
7 Windjammer: S/V Legacy X3, S/V Polynesia, S/V Caledonia, S/V Diamant, S/V Sagitta