I just got off of the Magic on 1/26 and on the tv, they had some promo shots of the Western Cruise and the proposed excursions:
From memory, they showed:
Key West -
see where Earnest Hemingway walked and lived
a Kayak excursion
Cozumel
Mayan Ruins, looked like Tulum
Submarine - looked more like the See and Sea in St Maarten and not a full submarine. It's more like a boat with a deck and when you get to the reef, you go below the deck for a short period and view the reef thru glass panels, then return to the deck.
Grand Cayman
horse drawn carriage tour
Swim with the Stingrays
Snorkel
Scuba
Atlantis Submarine