For the wrong reasons.
Halong Bay is a small part of the Gulf of Tonkin which captures rubbish, plastic waste etc. via prevailing easterly winds and seasonal currents. Casual observers may be forgiven for assuming all the debris comes from Vietnamese tour operations or coastal communities.
The plethora of cruise operators are regulated and must conform to strict rules which include no-overboard waste discharge, period.
I don't need full service on a 1hr 50m flight, nor lounge access, just a convenient schedule.
Da Nang's beaches certainly beat the pants off Pattaya, HuaHin and Patong. Hotels are inexpensive and service is superior. Taxis or Grab are very cheap but almost unnecessary as one can walk, or run, the wide beach promenade in safety. Bars and restaurants offer service around the clock although one shouldn't expect the same p4p scene as Thailand.
Its a diferent experience, but not a place I'd love to spend eternity. The city feels very clean yet at the same time, inefficicent through its over-orderliness. Case in point is tge homeless people I saw.
The city is nice for zoo lovers. And there are beaches there. But Sentosa where the main atteactions are, feels too much like the USA. Well if I wanted Caucasian, I'd get that at home.
Reminiscent of the slapping massage lady in BKK above the Chuchok temple