Ubundu, formerly known as Ponthierville or Ponthierstad, is a city located in Tshopo District of Orientale Province in the Democratic Republic of the Congo. It is on the Lualaba River, or Upper Congo, just above the Boyoma Falls. The river is not navigable from here downstream to Kisangani, so a portage railway was built to link Ubundu to Kisangani. Upstream from Ubundu the river is navigable as far as Kasongo.