I think you would like to have something weatherproof anyway... It's going to rain there now and then.
There will also be a lot of wildlife (birds, whales etc) that might interest you, so a longer lens will be handy.
You said earlier, that you have the PanaLeica 8-18... Don't know about the middle range in your bag, but I would like to have either the 12-40 or the 12-100 mm there; both seem to be exellent lenses.
And then the longer versions... 40-150 f2.8 Pro is the only one weatherproof - except the 14-150mm superzoom. IQ is different, anyay.
The other way to go is the old (and used) D.Zuiko 50-200mm f2.8-3.5 SWD. Get also the older TC14. Works fast on Em1, but not as fast as the 40-150 mm Pro. More reach, weatherproof. Also heavy and large, but not too much compared to 40-150 mm lens.
The SWD-version is the mkII of that lens and has a faster focus system. Solid performer.
I have that, bought it used about seven years ago (?). My main tele since then, especially in low light (and we have that in Finland a lot). For sunny days, hikes and travel I also have the small and light m.Zuiko 75-300 mk1 - a nice lens, no problems with IQ, but no weatherproofing. If you go that way, remember to buy a lens hood. Protects the front lens from the drops. With 50-200 you should get one anyway.
Have a nice trip!
PS. If you buy the 50-200, do the focus adjustment before the trip and test the fine tuning... Mine needed some -3 setting, and a bit more with the TC. Easily done, but needs a tripod.
Jouko
'The best camera in the world is the one you have with you when you need it'
https://www.instagram.com/jouko.k.lehto/
http://lehtokukka.smugmug.com/
http://jouko-lehto.artistwebsites.com/
https://joukolehto.blogspot.fi/ - Lenses for mFT-cameras
https://joukolehto.blogspot.fi/2015/12/what-to-dowith-camera-during-winter.html