Our favorite three walking areas are: Ásbyrgi, the wooded horseshoe canyon at the park's northern end; Hljóðaklettar and Rauðhólar, in the park center; and on the south end of the park, a triumvirate of waterfalls: Hafragilsfoss, Dettifoss, and Selfoss. All three areas could be crammed into one day, but two days or even three are preferable. Another prime walking area is Hólmatungur, with its luxuriant cascades and vegetation, but access is more limited.
This broad canyon, near Route 85 and west of the Jökulsá á Fjöllum River, forms a "U" shape about 3.5km (2 miles) north-to-south and 1km (1/2 mile) across, with a forested plain on the bottom and a rock "island" called Eyjan in the middle. Geologists believe Ásbyrgi was gouged out by catastrophic flooding from Vatnajökull somewhere between eight and 10,000 years ago, and again around 3,000 years ago. Apparently these flood bursts had 2,000 times the force of the Jökulsá á Fjöllum today. The river then shifted east to its current location, leaving Ásbyrgi dry. The Vikings had their own explanation for Ásbyrgi: clearly the god Óðinn's horse, Sleipnir, had left an enormous hoof print with one of his eight legs.
Walks in Ásbyrgi can start from the information office or from a parking area at the southern end of the "U," near the base of the cliffs. Route 861, which splits off from Route 85 at the N1 gas station, passes the information office and ends at the parking area. No favorite asserts itself among the walking routes; so, if you have a car, it makes sense to drive to the parking area and scan the many options from there. Beautiful ferns and orange lichen inhabit the cliff walls, along with 1,200 pairs of nesting fulmars. If you decide to see Ásbyrgi from the rim above, backtrack to the information center and find the trail leading to Tófugjá, where you can ascend the rim with the aid of ropes.
Hljóðaklettar & Rauðhólar
Hljóðaklettar (Echo Rocks) and Rauðhólar (Red Hills) form an ideal 2-hour loop hike, starting from a parking area shortly past the Vesturdalur campsite on the west side of the canyon. The trail has tricky footing in spots, but is not otherwise difficult. Leaflets describing the route should be available right at the trailhead. The trail weaves through some of Iceland's most intriguing basalt configurations, often eroded from below to form honeycomb patterns. The human-sized trees along the trail feel oddly companionable, and the woolly willow is easily recognized by its light-green, fuzzy leaves. Hljóðaklettar earned its name from certain locations where the sound of the river echoes and seems to come from the wrong direction. The best spot to witness this phenomenon is right by the marked turnoff for Kirkjan (Church), a fabulous cave once sought out by sheep during storms. Rauðhólar, a crater row tinted with red gravel, marks the northern end of the loop and has great panoramic views. Some trekkers take the bus to Vesturdalur and continue all the way to Ásbyrgi.
Hafragilsfoss, Dettifoss & Selfoss
Moving progressively upstream along the Jökulsá á Fjöllum River, the magnificent waterfalls Hafragilsfoss, Dettifoss, and Selfoss are a kind of appetizer, main course, and dessert. Hafragilsfoss, at 27m (89 ft.) high and 91m (299 ft.) across, is captivating and monstrously powerful. The best view is from the Sjónnípa lookout point, a 1km (1/2-mile) hike north from the parking area. Hafragilsfoss is overshadowed, however, by Dettifoss, Europe's mightiest waterfall. On average, the milky-gray glacial water cascades over the 44m (144-ft.) drop at a rate of 200 cubic meters (656 sq. ft.) per second. Selfoss is only 11m (36 ft.) high, but its unusual breadth and parabolic shape are well worth seeking out.
Most travelers see the waterfalls from the east side of the river, since the parking areas on the west side are not accessible to regular cars. Those in 4WD vehicles often approach Dettifoss from the west side, where the view is somewhat better. The SBA buses also stop on the west side. On the east side, however, views of Selfoss are slightly improved and Hafragilsfoss is much more accessible. The drive to the waterfalls from Ásbyrgi -- on Route 864, down the eastern side of the canyon -- takes about 40 minutes. Selfoss is reached by walking 1.5km (1 mile) south from the Dettifoss parking areas on either side of the river.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.