A Halong Bay cruise is the top thing to do in Vietnam - but the bay has become overcrowded, heavily polluted, and unsustainable. For a more ethical trip, look for a Halong Bay alternative like neighboring Bai Tu Long Bay, Vietnam, instead. Here's what to consider about Bai Tu Long Bay or Halong Bay, plus a guide to planning your trip. #Vietnam #HalongBay #BaiTuLongBay