The area is recognized as the World Natural Heritage that is the area of 434 sq. km with 775 islands. The islands in Halong Bay are mainly limestone and schist islands most lying in the two main areas: the southeastern part of Bai Tu Long Bay and southwestern part of Halong Bay.
These islands represent the most ancient images of a geographical site having a tectonic age of from 250 million to 280 million years.
Short treks can be provided on these islands. The boat trips drop their guests on one of these islands where they can make a short trek up to the peak. Longer trekking trails are also available in bigger islands. Vietnam trekking tours Halong bay may be what you would like to do while you are cruising on Halong bay. These trekking tours are optional.