I recently returned from a trip to Iceland, & it turned out to be a fabulous, fabulous place to write. Here are my tips for soaking up all the literary inspiration Iceland has to offer:
1) Stay someplace comfortable, preferably in the middle of nowhere. There's a lot of that in Iceland. And plenty of scenery to go around.
This is the Hotel Jökulsarlón, about 15 minutes from a glacier lagoon. Tell me that's not going to get your writing-wheels turning.
2) Do the thing. Break up your writing with experiences, especially things that bring your closer to what your characters encounter.
Does your character run from lava? Feel what it's like to be in a room with just a rivulet of fresh lava! 
Everyone who writes a character in the saddle needs to be in one themself. Icelandic horses are a very good first-time riding experience. And they are NOT ponies.
3) Educate yourself. History is full of inspiration, whether it's on a geologic or a human scale. Seeing a picture is not the same as smelling the air, or hearing how your footsteps echo in a space.
The Skógar Museum has recreated cottages & other historic structures you can enter.
The Perlan Museum has an ice cave you can traverse safely year round--so bring a good coat & a warm hat!
4) Nourish yourself. I did not expect to find so much good food in Iceland, but there was LOTS. Everywhere had good coffee. Some of the fusion restaurants were mind-blowing! And most astonishing, everywhere--& I mean EVERYWHERE--had perfect french fries.
Perfect.
French fries.
Of which I have no pictures, because I was too busy eating them.
All that to say, Iceland is an ideal writing retreat. It's a place where elves live in the rocks, reindeer refuse to be tamed, & you can spend the whole day in your slippers drinking Swiss mochas over your laptop & nobody bats an eye. Give yourself remarkable things to do, & your Muse will be hard-pressed to stay silent.