The top things to do in Diamond Circle are: Keflavik Airport (KEF): Bus Transfer to/from Reykjavik Reykjavik: Golden Circle Full-Day Tour with Kerid Crater Iceland: Northern Lights Bus Tour from Reykjavik Keflavik Airport & Reykjavik Hotels: Economy Bus Transfer From Reykjavik: South of Iceland Full-Day Trip Explore the best things to do in Diamond Circle on GetYourGuide