I like Everest too.
I like ASPEN & would have used it on one of mine...except, then I met a crazy girl with this name & don't want to associate my betta with her. haha
Also.... TUNDRA, MERCURY, JASPER, EUGENE (as in the very green Oregon city that rocks!),
CASCADE, FIRTH (forest), my Ghost Radar just said "CASEY" after being silent for an hour...LoL, so my ghost apparently likes that name.