Mya Davies, from Craven Arms, and her boyfriend Lewis Smith, from Wem, set off to on Friday to climb Ben Nevis in Scotland before attempting to conquer Scafell Peak in England on Saturday and Snowdon (Yr Wyddfa) in Wales on Sunday.
Lewis told the BBC that his dad had climbed Ben Nevis and Scafell Pike but had sadly died before managing to get to the summit of Snowdon.
"We wanted to challenge ourselves," he said. "The reason why we are doing it for the Severn Hospice because he was there at the end of his life.
"He climbed Ben Nevis and Scafell but never managed to see Snowdon. It will be an achievement now for us both."
Mya said they climbed Snowdon last September but had not done anything as extreme as this.
The couple have planned all their accommodation in advance and have supported each other in the gym.
"Lewis was there to push me, we will be keeping each other going," Mya added.
As of Friday they had raised more than £1,650 through their fundraising page - more than 330 per cent of their £500 target.
The fundraising page is at justgiving.com/fundraising/Mya-Davis