Press report doesn't say how they managed to get lost, but they used their mobile phone to alert emergency services at 11 at night. At this time of year, it remains light till 10 or so, so perhaps they weren't paying attention to the clock.
http://www.lavozdegalicia.es/se_galicia ... TO=4795299
http://www.lavozdegalicia.es/se_galicia ... TO=4795299