Finally got to answer my own question earlier in April 2016. First of all, I made an error on my inquiry: the Equinox is a larger Solstice class ship, not the Millennium ship referenced earlier. Nonetheless, the Solstice class ships have an upper deck-forward reached only by a 2-deck stairway from the nearest elevator-accessible deck; this alone limits some of the traffic except on sea days.

On those days, getting a lounger is more difficult between 10-3, so even upper deck space is tight; on port days, not an issue. As stated in an earlier post about going to the forward corner, if you position yourself looking out over the sea, it MAY be possible to be nude. On one port day, I spied two older Dutch ladies who had evidently been topless and covered up as I approached. Sensing that I had like-minded folks near me, I moved from my Speedo (no problem anywhere on the ship) to a thong, and after having them return to toplessness, went nude. Even though they were behind me, and probably aware of my condition, unfortunately they didn't join me. However, the next day was also a port day and the whole thing repeated itself.

Summary: speedos and female thongs/rios OK throughout all sun areas, male thongs probably OK in crowded areas (but why risk the cat-calls?), male thongs OK (somewhat common)on the upper "Solstice" deck especially on port days, cautious Solstice deck-nudity possible on port days especially if someone breaks the ice.

On the e-mailed satisfaction survey sent to all pax, I reminded Celebrity (and, by implication, Royal Caribbean its parent company) that an "Euro" deck would provide a unique amenity at absolutely no cost to the company giving a competitive advantage. Especially on trips to St. Martin/Maarten, one sees fellow cruise pax attired in nothing or next to nothing on Orient Beach. In speaking with two ladies recognized from the next table at dinner, they allowed that they always booked itineraries with St. Martin/Maarten so they could go "naked."

As always, Celebrity provides generally excellent food and service (even better than its parent RCCL)and could likely increase its market share with a "Euro" area. My advice is to likewise make this suggestion during surveys/correspondence with Celebrity and other cruise lines. And even though some board members might suggest some of the nudist charters, I find these less-than-desirable because of the discomfort level of many of the crew. A better, and more convenient solution is some sort of a sanctioned area on general cruises.