We've found it here aboard the new ship, the Carnival Splendor.
The winner, hands down, is the Mud Lounge in the Cloud 9 Spa. Couples book the private cavern for an hour, then slather each other with "chakra'' muds, wash under the streaming showers while resting on mosaic-covered benches (complete with slots in them for allowing the mud and water to stream through.) Then they can steam in the tropical rainforest area of the suite. Tab: $95 for a hour for two.
For those who prefer more traditional spa treatments, there are the Balinese-design couples massage rooms. After a deep tissue or Swedish ($269 for two), the staff then scurries away and leaves the couple alone in the gargantuan round whirlpool. The solitude costs extra: $45 for 30 minutes.
--- PHOTOS: Above right, the Mud Lounge. Left, couples massage room in the Cloud 9 Spa aboard Carnival Splendor. Photos by Jane Wooldridge / Miami Herald.