Travelers have mixed feelings about the Blue Lagoon as it is a bit commercialized, but in my opinion, the Blue Lagoon is a MUST day trip from Reykjavik! I shamelessly love the luxuriousness of the experience. It’s also a very easy trip from Reykjavik. There are a lot of detailed blog posts all over the internet about the Blue Lagoon, so I will just cover my top suggestions for a day trip to the Blue Lagoon from Reykjavik. I would recommend booking tickets a week or so in advance (or further) in winter in order to ensure that you can get a day that works for your schedule. We purchased the standard package which just includes entrance and a Silica Mud Mask. You do not need to buy any of the packages that provide robes or anything, these are just gimmicks to get more of your money. If you think you need it for warmth, you do not even have to be outside not in the water, you can enter the water from inside the facility. You should plan to spend at least half of a day at the Blue Lagoon (unless you are like my sister and require a full 8 hour day there).
We booked our transportation through Gray Line Iceland (https://grayline.is/), which was one of the cheapest options and they had incredible service! Two of the buses filled up when we were trying to leave the Blue Lagoon and they had another bus there within 10 minutes for the 5 people that couldn't get seats on the other two buses.
Bring warm clothes for before and after, a bathing suit, and a waterproof phone case or pouch so you can take pictures! The locker room area is very clean and the lockers are generally big enough to hold your stuff (although you might have to smash it in there). You are able to go in and out of the locker rooms as much as you want, we were concerned about that! You also have a bracelet that allows you to lock and unlock your locker and purchase drinks at the swim-up bar. There are employees walking around that can answer questions but are mostly there to ensure that you shower before going into the lagoon and that you dry off before coming back to the locker area. Body soap, conditioner, lotion, and hair dryers are free to use! It is highly recommended to coat your hair in the conditioner prior to entering the water.
It’s surprisingly hard to see even in the middle of the day at the Blue Lagoon, there is a lot of steam sitting on the water. We were still able to find our way to all ends of the lagoon including the swim-up bar and the mud mask hut. We did the Silica Mud Masks then we also got lucky and someone was coming around with samples of the Algae mask which is included in the more expensive packages. We spent the entire day at the Blue Lagoon, watching both the sunrise and the sunset which was definitely a magical experience! It was really easy to get in and out of the locker room area, so we just ate some bars that we packed for lunch. I left to take pictures at one point and they allowed me to leave and come back since all my stuff was still in the locker room. If you do not think the Blue Lagoon is the best option for you (or you can’t get enough of the winter water activities), then I would highly recommend checking out the public swimming pools in Reykjavik. There are several of them and you will be among all locals. The pools are naturally heated and there are several hot tubs varying in temperature. Here is the link to the best swimming pool in Reykjavik that the locals go to: http://reykjavik.is/stadir/vesturbaejarlaug