Lan Ha Bay is made up of around 300 karst islands and limestone sea rocks and can be found southeast of Cat Ba Island. As a geological extension of Halong Bay, Lan Ha Bay is equally as beautiful although it is less visited, less inhabited and therefore has the extra appeal of being a more peaceful place. Tra Bau area Tra Bau is encompassed by the jagged karst hilltops. Unlike other parts of the Halong Bay area, the karsts seem to form around this area, turning into its bay of sorts. The area is pretty much untouched. It is a wonderful place to catch the stars at night. It is one of the safest places for ships to anchor. The hills around protect Tra Bau from any ferocious winds. Most cruises around Lan Ha Bay will anchor overnight.