Heartbroken Carmel O'Sullivan has lost hope that her son will be found alive one year after his disappearance, but she is desperate for answers.
David O'Sullivan arrived in America in March 2017 ready to embark on a five-month trek of the Pacific Crest Trail from California to the Canadian border.
The 25-year-old was last heard from on April 7th 2017, when he sent an email to his family from Idyllwild - a town located in the San Jacinto Mountains about 100 miles east of Los Angeles.
The Midleton, Cork native was due to meet a friend in Santa Barbara but never showed up.
Carmel and her family have been "living in a nightmare" since David's mysterious disappearance.
The devastated mother told the Irish Independent, "You have to just continue, we have nothing new, searches are ongoing.”
She explained that her son arrived into unexpected difficulty with weather.
"When David went last year it was great when he arrived but unfortunately he did meet snow that shouldn't have been there in April when he passed Idyllwild, which he wasn't expecting,” she said.
"A lot of people would skip it and loop back, that's what he would have been planning as he doesn't have any experience with snow. The general feeling over there is that he did get into difficulties with snow and that something has happened, he has not been found since.”Aerial and land searches to find her son had been carried out.
Carmel added that another “big search” is planned for this week, one year after her son’s initial disappearance.
"It's a huge area to cover and with the density of the trees you can't see down into every ravine, there are boulders there that are bigger than some cars even, it's next to impossible to search every little area,” she told the publication.
She added,"Nobody has seen anything of him, there has been no activity on his bank accounts, they can't find a signal for his phone and his GPS watch wasn't modern enough for police to pin a location for him.
"Everything went against us really, we knew he could be weeks without phone coverage so the alarm didn't ring with us for a while, although whether that would have done any good or not, we will never know."
Both Carmel and her older son Niall have said that they are constantly waiting by the phone and computer.
"We've posted on the new PCT hikers page about David to ask people to keep an eye out for him," Carmel said.
"There'll be thousands going through the area this month and we're hoping one of them will even see something like an item of clothing.
"Police have told us that they're not going to do any more searches because I suppose they don't have the resources but also because in cases like this it's usually another hiker who comes across someone who is lost - it could take years or he might never be found," she said.
Heartbroken, she lamented that she “doesn’t feel” like her son is alive.
"We are hopeful that he is alive but I honestly don't know how he could be to be honest - there hasn't been any activity on his bank accounts and he hasn't been in touch with home, which is something he wouldn't do to us.
"I'd love if there was a story that he had banged his head but was safe somewhere but I can't see it myself at this stage.
"The day that we get the phone call with the news that his body has been found will be horrendous but what we're going through now is equally horrendous, we're living in this awful, awful nightmare.
"We still haven't got definite proof that he is gone, I need to know what happened and where he is.
DEVASTATED MUM OF MISSING CORKMAN - David O'Sullivan from Midleton, Co Cork, has not been seen or heard from since April 2017 when he went missing on a hiking trip from California to the Canadian border. We're speaking to his heartbroken mum, Carmel. #NpRedFM pic.twitter.com/7nyxDVI96p— Neil Prendeville (@NeilRedFM) February 6, 2018
"Life can't go on for us until we know, I couldn't dream of leaving the country - unless it was to America where the searches are ongoing- until we know, I can't go to events, I just can't even think of trying to move on until I know.
I miss him so much, I go through so many scenarios in my head about what might have happened, I dream about him at night and think about it all."
The description in his missing poster says that O'Sullivan has brown hair, blue eyes, wears glasses and stands at 5-foot-10.
Anybody with any information about O'Sullivan's disappearance is asked to call the Murrieta Police Department on 951-696-3615 or Detective Lawlor on 951-545-0030.
Donations to the search can be made here.