Monday, 6 February 2023 - Left Hanoi and drove to Ha Long Bay, boarded a riverboat for a multi-hour cruise among limestone islands and islets in misty and cloudy weather, observed local oyster farms and fishing boats, explored Cat Ba Island with a short drive to Trung Trang Cave complex, hiked about 300 yards through dimly lit caves with stalactites and unique rock formations, then returned to the boat for more cruising, and ended the day with dinner on board as the sun set over the bay.