• Bald Peak State Park: The suprisingly few pictures available on the Net suggest the area might be suitable for additional Hoth exterior shots and/or the entrance/exit to Echo Base as shown in this snapshot. The composite shows features clearly shot at Finse/Hardangerjøkulen but also what seems to be the mouth of a road tunnel that just might have been shot in Oregon. Doesn't Norway have tunnels? Sure, plenty, but as far as we know there are none wide enough to match what we see onscreen near or at Finse. An alternate option is of course that we're dealing with a size manipulated still pic or a matte painting.
• Wetland areas & other damp spots: More specifically the Fernhill Wetlands and the Jackson Bottom Wetlands Preserve. There are also manmade splashabouts: The Henry Hagg Lake and the Aquatics Center (in Forest Grove). The latter could e.g be relevant as an indoor pool shooting site. Far fetched? Not at all, considering that the scene where R2D2 falls into the Dagobah pond was shot in a (then) unfinished swimming pool at Skywalker Ranch (!). Our rough guess is therefore that some Dagobah scenes may have been shot at any of these locations
• Hi-tech area: Important computer and electronics industry giants like Intel, Tektronix and Matsushita have facilities in or near the area. Might be important considering that Industrial Light and Magic pioneered (and spearheads) the use of computers and computer controlled equipment in special effects.

"I almost got kicked out of school because I dropped out for thirteen days to work as an extra. We wore English made costumes designed for studio work. Wearing silver sprayed rubber boots at 29 below (= -20° F) was a bit chilly."