What natural vegetation does Hansen probably pass as he travels along a river in Borneo?

As Hansen travels along a river in Borneo, he likely passes through lush tropical rainforest, characterized by dense canopies of tall trees, diverse undergrowth, and a rich variety of plant species. This region is home to unique flora such as dipterocarps, ferns, and orchids, as well as a variety of palms and vines. The riparian zones along the riverbanks would also feature mangroves and other moisture-loving plants, contributing to the vibrant ecosystem. The overall vegetation reflects Borneo's rich biodiversity and complex habitats.