Tragedy struck while Cally Simpson was on holiday at the Villa Marina resort in Salou with her father Steven and grandmother.
The girl, from Arbroath, was pulled from the pool and attempts were made to resuscitate her. Yesterday she was said to be in a stable condition the Intensive Care unit at a children's hospital in Barcelona.
Her distraught grandmother said they still did not know how the youngster had ended up in the pool.
Wendy Simpson said: "This was her first ever holiday. She can't swim.
"We are all praying that she will pull through. There has been a slight improvement. They have started to raise her temperature to 36.5 degrees. She is now stable.
"We were all there, but we don't know what happened. The last time we saw her she was walking behind her dad to the main building. We have no idea how she came to be in the pool."
After enduring flight disruptions because of a strike by French air traffic controllers, Cally's mother Kate flew out to see her daughter yesterday.
A Facebook page, Saving Cally Simpson, was set up to raise funds to pay for the travel costs.
Messages of support have also been left on the site.
Sara Warren wrote: "My heart goes out to you and your family." And Louise Cargill wrote: "Come on cally auntie lous needing to see that cheeky smile love u loads xxxxx."
Family friend Koula McCracken said the whole of Arbroath is praying for Cally.