The National Parks System Is Reopening Hawaii's Once-Forgotten 'Hell Valley' For The First Time In 80 Years

There's more to the Aloha State than its spectacular outdoor landscapes. Hawaii is also home to important cultural monuments, including some with dark back stories, like Honouliuli National Historic Site. Honouliuli is an abandoned internment camp that the National Parks Service (NPS) is reopening this summer for the first time in 80 years. 

The camp, located in the depths of a dry, hot gulch in the Wai'anae mountains on the island of Oahu — hence its nickname, "Hell Valley" — was the archipelago's largest incarceration and internment site, and was open the longest. It's notable that, including Honouliuli, there were 17 detention sites during World War II located throughout the Hawaiian islands. During its three-year run from 1943 to 1946, the U.S. government unjustly detained around 400 civilians of Japanese and European ancestry without charge or trial at Honouliuli, as well as around 4,000 prisoners of war, most of whom were of Okinawan or Korean heritage. 

The camp closed after the war, and apart from the collective memory of the prisoners who survived it, Honouliuli was practically forgotten. Its existence barely registered on the island's official history until 2002, when its remains were searched for and discovered by volunteers from the Japanese Cultural Center of Hawai'i. President Barack Obama designated the site as a National Monument in 2015, and a few years later, Congress made it a National Historic Site. Along with the historic temple of Puʻukoholā Heiau, it's actually one of only two national historic sites in Hawaii. 

When you picture an unforgettable trip to Hawaii, you imagine snorkeling with sea turtles, epic volcano hikes, or an outrageously gorgeous island-hopping tour. Yet this new site is a chance to see a whole other side of the islands. On July 18, 2026, eight decades after the internment camp closed, the National Parks Service is opening the partially restored Honouliuli National Historic Site to the public on a limited basis. On June 4, the NPS released a series of six free public tour dates, the first ever to be offered at the site, for 2026. All the spots were quickly filled, with waitlists of hundreds more people hoping for cancellations.

Each tour lasts about three hours and accommodates a maximum of 22 participants. Excursions start promptly at 8:15 a.m. on select Saturday mornings, departing from Hawaii's Plantation Village, an outdoor museum focused on Hawaii's sugar plantations. A shuttle bus will transport the group into the gulch. From there, the tour involves hiking and walking along unshaded trails past the camp's historic structures. Each outing is a chance to learn about the once-forgotten internment camp and its prisoners from a knowledgeable guide, witnessing an important part of Hawaiian and American history. There are not (as yet) many visitor facilities. Visitors must wear closed-toed walking shoes and bring at least two liters of water. Visit the NPS website to join a waitlist.

To learn more about World War II history on the island, consider the Pearl Harbor Warbirds tour, a unique history tour that gives visitors a rare scenic view over Pearl Harbor. Like diving with sharks or catching a wave at Waikiki Beach, it's an amazing experience you can only have on Oahu.