If you need an English-Icelandic dictionary or an Icelandic-English dictionary, you've come to the right place. This is a subscription-based website but the subscription fees are very affordable. You'll also find here a Danish-Icelandic and an Icelandic-Danish dictionary, as well as an Icelandic spelling dictionary. Those are still in development and are include free of charge with the subscription.

English-Icelandic and Icelandic-English dictionary (200,000 headwords).
Danish-Icelandic and Icelandic-Danish dictionary (45,000 headwords).
Spelling dictionary (80,000 headwords).

Create your subscription here.

It's worth noting that you can choose between a subscription to ordabok.is and the software package Tölvuorðabókin. See the comparison.

Find price details here. What do subscribers say about ordabok.is? A few interesting points about the website.

You can get a trial subscription here.