From what I can gather UL has two lounges. Serenediva and Serendib
Serendib is by far the better and is limited to pax in business class or higher. Serendiva is in a bit of a far away corner and is for most economy pax. The whole UL lounge access policy is a bit complex:
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Curiously, as I found out, if you qualify for Serendib access, they won't let you into Serendiva. The reason I wanted to use Serendiva was that I had booked a room in the Serendiva Transit Hotel which is co-located with the Serendiva lounge. It would have been more convenient, being right next door to the hotel room.