Wednesday, December 22, 2021

Halemau'u Rainbow Bridge

Halemau'u Rainbow Bridge and Haleakala Crater
2.5 miles round trip, 500 feet elevation gain
Difficulty: Easy
Access: Paved road to trailhead, Haleakala National Park entrance fee required

As Maui’s Haleakala Volcano rises over 10000 feet from the surface of the Pacific Ocean, the lush tropical forests of its lower windward slopes transition to the barren rock and colorful cinder cones of its massive crater. The short hike along the Halemau’u Trail in Haleakala National Park to Rainbow Bridge, a spectacular ridgetop viewpoint, gives hikers a great overview of this transition zone and packs in some stunning views. The name can be slightly misleading, as there’s no arch of any sort here: Rainbow Bridge refers to a narrow stretch of ridge with views to both sides. The Halemau’u Trail extends beyond Rainbow Bridge, descending into Haleakala Crater to connect up with the Sliding Sands Trail that descends from the summit, but a traverse of the crater is likely too much for most casual hikers, who will find this easy hike to Rainbow Bridge to be sufficiently rewarding.

Anna and I hiked to Halemau’u Rainbow Bridge during a December trip to Maui. We had initially intended to do a more extended hike in Haleakala Crater that day, but after rushing out of our hotel at 3:30 AM on our way to see the summit sunrise, I realized that I had failed to bring a backpack containing our lunches and my camera. Thus, rather than doing a more extended hike along the Sliding Sands Trail, we chose to do two short excursions on the Halemau’u and the Sliding Sands Trails.

From Kahului, we followed the Hana Highway east from town for 3 miles and then turned right at the traffic light with the Haleakala Highway (Highway 37). We followed Haleakala Highway uphill along the volcano’s lower slopes for 8 miles and then turned left to stay on the Haleakala Highway (now Highway 377) after entering the town of Pukalani. After another 6 miles, we made another left turn to stay on the Haleakala Highway (now Highway 378) after passing Kula Lodge; we followed this road as it climbed aggressively through many switchbacks for another 16 miles, entering Haleakala National Park and then arriving at the Halemau’u Trailhead. The trailhead is well-marked and lies at the northeastern edge of a switchback, with a parking lot on the left side of the road. The road is extremely windy and gains a lot of elevation but it is paved the entire way; however, a few bridges along the way are only wide enough for one car so slow down to yield when approaching these bridges. Additionally, reservations are required to enter Haleakala National Park before 7 AM due to the intense popularity of the summit sunrise; if you’re not coming for the sunrise, wait until after 7 to enter the park.

The forests characteristic of the lower slopes of Haleakala had faded to brush by the time we reached the Halemau’u Trailhead, so we had good, open views of the island and the Pacific Ocean from the parking lot already. A nene- an endemic Hawaiian goose that rarely flies and inhabits the upper elevations of Haleakala- was hanging out in the parking lot, enjoying the view. From the trailhead, we followed the Halemau’u Trail from the far end of the parking lot. The trail traveled through high brush as it descended gradually while it headed northeast towards the rim of Haleakala Crater. After two-thirds of a mile hiking from the trailhead and about 200 feet of descent, we came to a junction with the trail from Hosmer Grove; we stayed right at the junction to stick to the Halemau’u Trail, which continued descending as it approached the rim of the crater.

After the junction, great views opened up to the north of the heavily forested windward side of Maui. The northeast side of the island catches moisture moving across the Pacific that stalls when it meets Haleakala: the result is over 100 inches of rainfall each year, with superlative years recording up to 400 inches of rain. As expected, there were some clouds playing with the mountains on the windward north slope of the mountain, so even though we could see many of the lush ridges on the upper slopes and the Pacific Ocean in the distance, we only caught occasional glimpses of the rainforests of Koolau Gap during rare cloud breaks.

Haleakala slopes
Lush slopes of Haleakala
About a hundred meters past the junction, the trail came to its first viewpoint of Haleakala Crater. A stunning panorama of multi-layered volcanic cliffs towering above a great sloping plain dotted with colorful cinder cones opened up. Hanakauhi, a massive peak that marked the northeast rim of the crater, rose majestically on the other side of the plain. A forested ridge jutted out below and ahead of us into the crater: we could see the Halemau’u Trail’s many switchbacks down the side of the ridge to the crater floor which, luckily, we would not have to traverse on that day. Unlike the view of the crater from further up the volcano at Red Hill, the view from the Halemau’u Trail was less barren and substantially more green: grasses covered the crater floor here, making for a lusher scene than the austere landscape of ash further up the mountain.

Hanakauhi rising over the Haleakala Crater
As we descended via switchbacks, we could feel the vegetation around us begin to transition: the brushy vegetation at the trailhead, on the leeward side of the mountain, was now being replaced by ferns and other moisture-loving plants on the windward side. After just over a mile of hiking and nearly 500 feet descent from the trailhead, we came to the Rainbow Bridge stretch of the hike, where the trail followed the narrow crest of a fin-like ridge with spectacular views off both sides. This stretch of trail was thrilling without actually being dangerous. The views of the crater rim walls on our side of the crater were more impressive here as we were essentially within the crater at that point.

Halemau'u Rainbow Bridge
While some hikers may choose to head back from here, a more natural and satisfying turnaround point is just a little further down, at the prow of the fin-like ridge. We continued following the trail, which hugged the north side of the ridge with constant spectacular views down towards Koolau Gap. About a hundred meters further along, we came to the end of the ridge, where the trail made a 360-degree turn and wrapped around to the other side of the ridge to begin its long, switchbacking descent to the crater floor. A short spur trail at this turn led to a small promontory at the very end of the ridge; we walked out to this high point, which provided the most spectacular view of the hike. Hanakauhi rose across the plains of Haleakala Crater from us, while the sloping crater floor led up towards the lava-covered heart of the volcano below Red Hill. Holua Cabin was the only visible sign of human presence here, a lone hut dwarfed by volcanic cliffs and the immensity of the shield volcano landscape around it.

Rim of Haleakala Crater
This was an incredible viewpoint from which to study the ecological transition zones on Haleakala: a natural textbook was open before us. To the right of the view, we could see the alpine summit of Haleakala, where winters are cold, snow falls occasionally, and the ground is dominated by ash from the cinder cones. The Pu’u O Maui and Ka Moa o Pele cinder cones were among the most prominent with their high and agreeably asymmetric forms. From the cinder cones, black lava flows led downslope: the upper stretches of the lava flows looked entirely desolate, but at a certain point grasses began appearing and then shrubs. As the crater opened into Koolau Gap, the bushes gradually transitioned into rain forest. The lower slopes of the volcano were not visible below the clouds, but we would experience it as a waterfall-dotted rainforest later on our drive to Hana.

Looking up the Haleakala Crater to the cinder cones
Hiking the first stretch of the Halemau’u Trail was a thoroughly enjoyable experience and a must-do on Maui. I’ll certainly have to return to Haleakala to visit the spectacular crater floor in the future.

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