We got this transfer from Reykjavik to the blue lagoon and it was really straight forward. The drivers picked us up on time both times so we didnt have to wait outside in the cold. If you are being picked up from Reykjavik first you get onto a minibus that takes you to the terminal and then you get on the large bus. It was really simple and easy.

We booked separate transport and blue lagoon tickets on the last day of our trip and took our luggage to travel on to Keflavik Airport. The transport was fine however I was told the last coach to Keflavik was at 2.30 however on the day the driver said there was a coach at 4. We had a very enjoyable experience at the blue lagoon and could have stayed longer but caught the 2.30 coach as booked. This meant we had a long time at the airport. We were travelling with our 14 year old who was classed as an adult fare. In retrospect it would have cost the same for a private taxi for the three of us. While the coach service itself was fine I recommend looking into other options before booking

You initially get picked up by mini bus from a pre-arranged bus stop in the city centre (Reykjavik) and then transfer to the larger coach at the bus terminal. The drivers are very helpful, they have a list of who they are expecting and they tell you which coach to change to, so all in all, it's a pretty smooth operation.