Diving & Snorkelling
One of the most otherworldly activities in Iceland is donning a scuba mask (or snorkel) and dry suit and exploring the crystalline Silfra fissure, one of the cracks in the rift valley. There's also a rift, Davíðsgjá, out in Þingvallavatn lake, which is harder to reach. You must book ahead with a Reykjavík dive operator. People with their own equipment must have licences, dive in groups of at least two, and buy the permit (1000kr) from the visitor centre or www.thingvellir.is
Check in with park centres for lake fishing rules (some areas are off limits, and any imported equipment must be disinfected), and get a permit (2000kr per pole per day; May to mid-September) from the Information Centre. The fishing card offering fishing access to multiple locations (www.veidikortid.is) also covers part of Þingvallavatn.
In the valley on the Rte 36 approach from Reykjavík, you can go horse riding and mountain biking with Laxnes.