I was surprised to learn that the lagoon itself is actually manmade, with its water heated by the nearby geothermal power plant, Svartsengi (look for it just before you pull into the parking lot). Entering the lagoon is a process unto itself. The narrow walkway surrounded by rocks on either side makes for a very tranquil first impression of the grounds. After all, it is a place of healing which Icelanders have enjoyed and respected since the 1970s, when the water was just some unexpectedly nice runoff from the power plant.
One thing I would highly suggest is purchasing your entry ticket online instead of waiting to buy it at the lagoon, as visitors with pre-purchased tickets get priority entrance. The front desk employee will then issue you a wristband that's linked to your "account," a payment tab system which allows you to buy refreshments and open your locker.
After you're done checking in, you'll be directed to the locker roomeither male or female depending upon, well, you know. Select a locker, strip down to either a towel or your bare essentials, and then head to the showers. Want to bathe in the lagoon? You have to bathe yourself first. Don't worry, as they have private shower stalls if you're not comfortable showing off your birthday suit.
When you're done soaping up in the shower, you'll head into a room that will give you your first unobstructed, albeit indoor, view of the Blue Lagoon's majestic waters. Simply head down the stairs, out the door and you're face-to-face with the most beautiful blue water you've ever seen. No need to test it; the water's fine, I promise.
To start planning your trip to the Blue Lagoon, check out their official site.
[Photos: Andy M]