I've visited the Dalvik area many times (lucky me!) and this was my favorite place to stay. The setting right along the water is beautiful, peaceful, and ever-changing with the light and weather. There are all kinds of birds all around, and the songs of bird calls was a constant companion. Some ptarmigans also liked to hang around right nearby, which was especially neat to see. I did not happen to see a whale, but I've got to imagine they swim right by the windows.
The cabin itself is very nice - a 'just right' small size for one person, but would work great for a couple, too. The kitchen is tiny, but fully functional, the bed was very cozy, and I slept peacefully every night. Wifi works great. Overall it was nicer than I expected.
The hot tub is a major bonus. After an excellent day of skiing, I'd proceed directly to the geothermal water to warm up and bask in all the fun I just had. The hot tub was also nice for a pre-bedtime soak.
Location-wise, these cabins are about 12 minutes from Dalvik and 25-30 minutes from Akureyri. There's a row of 6 or so cabins on this property, but they are spaced out enough that you have plenty of privacy.
Definitely recommend staying here, and I'm already looking forward to coming back on my next visit.