Called by the people of Papua New Guinea "Siassi," Umboi Island, in Morobe Province, is the largest of the volcanic islands between the mainland and New Britain Island. During World War II, it was called "Rooke Island." It is a complex volcano with no historic eruptions and is about 900 square kilometers in area, with the greatest length at 50 kilometers.
Between 1994 and 2004, creationist living-pterosaur investigators explored the island five times, searching for what villagers call "ropen." There were two sightings during the two 2004 expeditions (by Luke Paina  and David Woetzel ), both from a distance and at night, but many eyewitnesses were interviewed. The information gathered contributed to two more successful expeditions (Nation and Kepas) to the mainland: November of 2006, and March of 2007, in the earlier of which two indavas (believed to be similar to the ropen, or even the same species) were videotaped.
Living-pterosaur investigators exploring Papua New Guinea or interviewing natives have included missionary Jim Blume, Jacob Kepas, Carl Baugh, Bob Summers, Paul Nation, Nathanael Nation, Jonathan Whitcomb, David Woetzel, and Garth Guessman.
- Umboi Island
- Umboi, Ritter, and Sakar Islands
- Global Volcanism Program: Umboi
- Whitcomb, Jonathan. Searching for Ropens. California: Bookshelf Press, 2006