Lava Water Accommodation is comprised of various units on an organic sheep farm. We stayed in what is described on hotels.com as a one bedroom apartment but which is actually a cute little self-contained cottage (and haven't seen the other units). It's like staying in one of those perfect little demonstration areas you see in IKEA stores. We couldn't explore the farm itself as there are so few winter daylight hours and we were out and about, but it's a great base camp for a circuit of the Snaeffelsnes Peninsular. I am generally wary of very small, independently run places, as you often need to call in advance for check-in codes or to visit another location first to get the key, but this couldn't have been easier. But you do need to plan in advance and arrive with groceries, as the nearest supermarket is approx. 25 miles away. Or you could eat at the small restaurant a few miles down the road. The only complaint in the cottage is that a child-size bunk bed has been added over the pillow ends of the twin beds and it creaked and moved during one especially windy stormy night. Otherwise, it's picture perfect.
Note: As of December 2018, approx 10 small houses/rental units are being built adjacent to the farm, so there will be a little more traffic and activity starting in 2019.