The box also contains packets of lubricant and HIV test information, and will be replenished weekly.
Rolf Martin Angeltvedt of the charity Gay and Lesbian Health told Osloby
(in Norwegian), "It is located on the path at the campsite. The hole is plugged so that no birds can come in, and then there is a small wooden penis attached on the outside so that it is easy to spot."
The video on the Osloby website shows the men installing the box.
explains that gay men who go 'cruising', seeking anonymous sex with strangers in public places, are at a higher risk of contracting sexually transmitted diseases, and Ekeberg Forest is apparently a popular venue for such encounters.
"If there is too much shame associated with your own sexuality, your may take greater risks or treat yourself and others worse," he added.