Castaway Cay (pronounced "key") is Disney Cruise Line's original private island, leased from the Bahamian government since the late 1990s. Tucked into the Abacos chain, it's the only Caribbean private island where ships dock pierside instead of tendering — a practical advantage that means you can step off the gangway and be on the sand in 10 minutes, then come back to the ship for lunch or a nap whenever you like.
For most Disney cruise families, Castaway Cay is the highlight of the trip. The beaches are quiet (only Disney passengers — typically one ship per day), the lunch is included in your cruise fare, the snorkel trail is one of the best easy-snorkel experiences in the Caribbean, and the whole day runs on Disney logistics: a tram from the gangway to the family beach, lifeguards everywhere, free fruit stations, and free water you can refill all day.
A few things to know going in: weather can cancel the stop (Disney reroutes 5–10% of Castaway calls per year due to wind), the adults-only Serenity Bay is a 15-minute walk or a tram ride from the family beach, and the most popular extras (cabanas, parasailing, the 5K medal) sell out the moment booking opens at 90 or 75 days before sailing.