What day and time of the week tend to be the least crowded?
Blue Lagoon is one of the most popular tourist attractions in Iceland. There are limits on how many guests can visit at each time and, most often, the Blue Lagoon is fully booked until late afternoons 1-2 days in advance.
We highly recommend that you pre-book your ticket well in advance, to be sure that you can fit the Blue Lagoon in your Iceland travel schedule.
If you plan to visit without having pre-booked your entrance ticket, we can't guarantee an entrance ticket. In fact, it's very unlikely, especially if you are arriving before 18:00. Evenings are more suitable for walk-in guests, but again - we can't emphasize this enough - the only way to guarantee admission is to pre-book online.
The limited availability is because of the number of lockers in the changing rooms. The Blue Lagoon it self is big; you can always find a secluded spot by wandering further into the lagoon, away from the main building.