The Haʻikū Stairs, also known as the Stairway to Heaven or Haʻikū Ladder, is a steep hiking trail on the island of Oʻahu. The trail began as a wooden ladder spiked to the cliff on the south side of the Haʻikū Valley. It was installed in 1942 to enable antenna cables to be strung from one side of the cliffs above Haʻikū Valley to the other. A building to provide a continuous communication link between Wahiawā and Haʻikū Valley Naval Radio Station was constructed at the peak of Puʻukeahiakahoe, elevation about 2,800 feet (850 m). The antennae transmitted very low frequency radio signals from a 200,000-watt Alexanderson alternator in the center of Haʻikū valley. The signals could reach US Navy submarines as far away as Tokyo Bay while the submarines were submerged.

Master Sergey Suprun uses a portable radio set as he stands near a rotary dredge which works on the coal face of the Borodinsky opencast colliery, near the Siberian town of Borodino, east of Krasnoyarsk, Russia October 27, 2015. The Borodinsky colliery, 9 km (5.6 miles) long and more than 100 meters (328 feet) deep, annually produces more than 20 million tons of coal and is considered to be the biggest opencast coal mine in Russia, according to official representatives. (Photo by Ilya Naymushin/Reuters)

(L to R) British model Leomie Anderson, English singer and television presenter Rochelle Humes, British television presenter from Blackburn AJ Odudu and English television, radio presenter and DJ Maya Jama attend the GQ Men Of The Year Awards in association with BOSS after party at The House of MOTY on November 16, 2022 in London, England. (Photo by David M. Benett/Dave Benett/Getty Images)

In this photo provided by Greenpeace, clothes are left to dry on a typhoon damaged tree in Surigao City, southern Philippines on Monday December 20, 2021. The governor of a central Philippine province devastated by Typhoon Rai last week pleaded on radio Tuesday for the government to quickly send food and other aid, warning that without outside help, army troops and police forces would have to be deployed to prevent looting amid growing hunger. (Photo by Jilson Tiu/Greenpeace via AP Photo)

British television and radio presenter Maya Jama attends the GQ Men of the Year Awards at Tate Modern on September 5, 2018 in London, England. (Photo by Splash News and Pictures)

Lady Gaga left her hotel to party in the east end of london for the night on September 10, 2016. She was wearing shiny hot pants and a little crop top showing off some under boob. But had sticky tape covering her nipples. Lady Gaga and Mark Ronson performed her new single “Perfect Illusion” at the General Browning Club in Hackney. Afterwards she went with a few friends to Metropolis strip club in Hackney. Lady Gaga left at 4am and returned to her Hotel. (Photo by Splash News and Pictures)

In this July 20, 2019 photo, children play during a sports event organized by members of the Caracas FC soccer club, in Catia, one of the poorest slums in Caracas, Venezuela. When the Caracas Football Club plays, its supporters leave their ideological preferences and socioeconomic differences behind, joining together to support and take care of each other inside and outside the stadium. (Photo by Matias Delacroix/AP Photo)

A couple covered with the US and the pride flags pay their tribute for the victims of a 12 June mass shooting in Orlando, Florida, USA, as they look at the Eiffel tower, illuminated in rainbow colours, in Paris, France, 13 June 2016. A total of 50 people including the suspect were killed and 53 were injured in a shooting attack at an LGBT club in Orlando, Florida, in the early hours of 12 June. The shooter was killed in an exchange of fire with the police after taking hostages at the club. (Photo by Yoan Valat/EPA)