The Golden Circle is the day trip almost every first visit to Iceland starts with, and for good reason. A single loop out of Reykjavik strings together three of the island's headline sights: Thingvellir, where the North American and Eurasian plates pull visibly apart and the old parliament once met; the Geysir field, where Strokkur fires a column of boiling water skyward every few minutes; and Gullfoss, where the Hvita river drops in two thundering steps into a canyon. Most tours add a fourth stop, usually the red caldera at Kerid or a soak in the Secret Lagoon. Below are the most popular versions, from the classic full-day bus to small groups that fold in the Blue Lagoon, with what each one includes, how long it runs and what it costs.